Genotoxicity risk assessment in fish (Rutilus rutilus) from two contaminated rivers in the Kosovo.

Being exposed to untreated urban and industrial water, the rivers Drenica and Sitnica are considered to be the most polluted ones in the Kosovo. Our previous investigations on the cyto- and genotoxic potential of water samples from these rivers evaluated with primary rat hepatocyte cultures indicated a risk for the health of aquatic organisms. In order to assess the genotoxic risk to aquatic organisms, we therefore performed a two year study (2016-2017) on roach (Rutilus rutilus) from these rivers. Specimens were collected at three locations along the Drenica river and two locations along the Sitnica river, and the genotoxicity was evaluated by the micronucleus as well as the Comet assay (DNA damage) in erythrocytes. The frequencies of micronucleated cells were determined for samples collected in four seasons, whereas the Comet assay was employed on samples collected in five seasons during the two-year period. The data obtained revealed an increase of the frequency of micronucleated erythrocytes from Rutilus rutilus collected at most sampling locations and from both rivers at all seasons investigated. Significant differences to the control (lake Badovc) were found in summer 2016 and spring 2017 samples. When comparing the seasons, the summer 2016 samples were most genotoxic, followed by spring 2017 and autumn 2016. With regard to the Comet assay data, a similar but more prominent "response" was observed. Another important observation is that micronucleus rates as well as DNA damage levels were significantly higher in samples collected in 2016 compared to the respective seasons in 2017. Altogether, the "response" obtained with both markers confirmed a genotoxic risk for fish due the pollution of these rivers. Since there were, however, seasonal and annual variations of the genotoxicity levels further in depth studies have to be carried out addressing the nature of these changes.

River pollution in the Kosovo: Cyto- and genotoxic effects of water samples in the primary rat hepatocyte assay.

The actual stage of the development of Kosovo is characterized by the concerning levels of environmental pollution and the serious health problems attributed to the emission of pollutants into air, soil and water. In this context, river pollution is one of the main threats due to the discharge of untreated urban and industrial waste waters that affect the quality of surface and ground water. In addition, urban and agricultural discharges are affecting the river water quality. In this article, we are presenting data on the cyto- and genotoxic potential of water samples from three rivers (Sitnica, Drenica and Lepenci) in the Kosovo as determined in the cultures of primary rat hepatocytes. Sitnica and Drenica (as the most important Sitnica tributary) drain into the Black Sea, whereas the Lepenci river drains into the Aegean Sea. These rivers are polluted mainly by industry in the Kosovo together with municipal discharges. The results of this study show that the samples have primarily a cytotoxic potential by causing necrotic cell death that was not accompanied by any increase of the rate of micronucleated cells as an indicator for a genotoxic potential. The different effects in 2 consecutive years can be attributed to variations in physico-chemical parameters such as water levels, intake of pollutants, and so on, indicating the need for continuous monitoring and risk assessment.

Effects of ß-Carotene and Its Cleavage Products in Primary Pneumocyte Type II Cells.

ß-Carotene has been shown to increase the risk of developing lung cancer in smokers and asbestos workers in two large scale trails, the Beta-Carotene and Retinol Efficacy Trial (CARET) and the Alpha-Tocopherol Beta-carotene Cancer Prevention Trial (ATBC). Based on this observation, it was proposed that genotoxic oxidative breakdown products may cause this effect. In support of this assumption, increased levels of sister chromatid exchanges, micronuclei, and chromosomal aberrations were found in primary hepatocyte cultures treated with a mixture of cleavage products (CPs) and the major product apo-8'carotenal. However, because these findings cannot directly be transferred to the lung due to the exceptional biotransformation capacity of the liver, potential genotoxic and cytotoxic effects of ß-carotene under oxidative stress and its CPs were investigated in primary pneumocyte type II cells. The results indicate that increased concentrations of ß-carotene in the presence of the redox cycling quinone dimethoxynaphthoquinone (DMNQ) exhibit a cytotoxic potential, as evidenced by an increase of apoptotic cells and loss of cell density at concentrations > 10 µM. On the other hand, the analysis of micronucleated cells gave no clear picture due to the cytotoxicity related reduction of mitotic cells. Last, although CPs induced significant levels of DNA strand breaks even at concentrations ≥ 1 µM and 5 µM, respectively, ß-carotene in the presence of DMNQ did not cause DNA damage. Instead, ß-carotene appeared to act as an antioxidant. These findings are in contrast with what was demonstrated for primary hepatocytes and may reflect different sensitivities to and different metabolism of ß-carotene in the two cell types.

Is there a relationship between genetic factors and the incidence and severity of H1N1 in Kosova?: A preliminary investigation and pointers for further research.

BACKGROUND: Host genetic factors may impact susceptibility to infection. A small number of studies have investigated the association between factors such as ABO blood groups and selected phenotypes on the incidence and severity of H1N1 infections with inconclusive results. METHODS: Using data from the Clinic of Infectious Diseases - University Clinical Centre Prishtina and based on the examination of 125 patients hospitalized with H1N1 in the period 2009-2014, the frequency of blood groups from ABO and Rhesus (Rh) systems as phenotypical markers were evaluated. In addition, other phenotypes such as ear lobe free/ear lobe attached, normal chin/cleft chin, tongue roller/non roller, hand clasping right thumb over/hand clasping left thumb over, right-handed/left-handed, dark eyes/light eyes were also analyzed. The data obtained from the 125 hospitalized patients were compared with the data from the Kosovar population (n = 2000) as a reference group. RESULTS: A total of 303 patients with H1N1 were hospitalized in the period 2009-2015. Blood group and phenotype data available from 125 hospitalized H1N1 patients showed significant differences in the frequencies of the blood groups from Rh system as well as in two (out of six) phenotypes of the selected morphological traits compared to reference groups. CONCLUSIONS: The findings from this preliminary study indicate that these Rh system and phenotype differences may be linked to H1N1 susceptibility and may guide identification of risk groups and populations.

Genotoxicity of lipid oxidation compounds.

Lipid peroxidation, the oxidative degradation of membrane lipids by reactive oxygen species generates a large variety of breakdown products such as alkanes, aldehydes, ketones, alcohols, furans and others. Due to their reactivity aldehydes (alkanals, 2-alkenals, 2,4-alkadienals, 4-hydroxyalkenals) received a lot of attention, in particular because they can diffuse from the site of formation and interact with proteins and nucleic acids thus acting as second toxic messengers. The major aldehydic peroxidation product of membrane lipids is 4-hydroxynonenal (HNE). Since HNE and other 4-hydroxyalkenals are strong alkylating agents they have therefore been considered to be the biologically most important peroxidation products. Although initially research focused on the toxicological potential of these compounds it is now well known that they play also a crucial role in cell signaling under physiological and pathophysiological conditions. Thus, it is obvious that the biological effects will be determined by the intracellular concentrations which can trigger adaptation, DNA damage and cell death. This review will not cover all these aspects but will concentrate on the genotoxic properties of selected lipid oxidation products important in the context of pathophysiological developments together with a chapter on epigenetic modifications.

Cyto- and genotoxic potential of water samples from polluted areas in Kosovo.

Reports on the state of the environment in Kosovo have emphasized that river and ground water quality is affected by pollution from untreated urban water as well as the waste water from the industry. One of the main contributors to this pollution is located in Obiliq (coal power plants). Prishtina-the capital city of Kosovo-is heavily influenced too. Furthermore, the pollutants combined together with those from heavy traffic are dissolved in Prishtina runoff water, which is discharged into the creek entering the river Sitnica together with urban waste water. The available data show the complex pollution with excessive quantities of nitrites, suspended materials, organic compounds, detergents, heavy metals, polychlorinated biphenyls, etc. In this study, the cytotoxic and genotoxic potential of water samples taken at these sites was tested in primary rat hepatocytes. The results obtained indicate that water samples collected in Prishtina and Obiliq had a significant cytotoxic potential in primary rat hepatocyte cultures even when diluted to 1 %. The increased cytotoxicity, however, was not accompanied by an increased genotoxicity as measured by the percentage of micronucleated cells. Further investigations addressing the chemical composition of the samples and the identification of the toxicants responsible for the cytotoxic effects found will be carried out in a next step.

Effects of pollutants from power plants in Kosova on genetic loads of Drosophila melanogaster.

It has been reported by the Ministry of Environment in Kosova that particle emissions from one of the units of the coal-fired power plants (Kosova A) in Kastriot/Obiliq were exceeding the European standard by some 74 times. Besides the particle emission, there is also release of sulphur dioxide, mono-nitrogen oxide (NOx), carbon monoxide, carbon dioxide, organic compounds and heavy metals. In addition, there is also release of heavy metals and organic compounds from a nearby solid waste dumpsite. Together, they are considered to be responsible for the increased health problems of the population living in the vicinity.To study the genetic effects of these emissions we focused on the genetic load, that is, recessive mutations that affect the fitness of their carriers, of exposed wild living Drosophila melanogaster The effects of ash from the dumpsite on the other hand were investigated upon feeding the ash with the nutrient medium. Our results revealed that the D. melanogaster population from the Kastriot/Obiliq area carries a high genetic load of 54.7%. Drosophila fed with the nutrient medium containing ash in a concentration of 1% carried a genetic load of 37.1%, whilst increasing concentrations (2% and 3% of ash) led to higher genetic loads of 68.7% and 67.4%, respectively.

4-Hydroxy-nonenal-A Bioactive Lipid Peroxidation Product.

This review on recent research advances of the lipid peroxidation product 4-hydroxy-nonenal (HNE) has four major topics: I. the formation of HNE in various organs and tissues, II. the diverse biochemical reactions with Michael adduct formation as the most prominent one, III. the endogenous targets of HNE, primarily peptides and proteins (here the mechanisms of covalent adduct formation are described and the (patho-) physiological consequences discussed), and IV. the metabolism of HNE leading to a great number of degradation products, some of which are excreted in urine and may serve as non-invasive biomarkers of oxidative stress.

Oxidative stress and the homeodynamics of iron metabolism.

Iron and oxygen share a delicate partnership since both are indispensable for survival, but if the partnership becomes inadequate, this may rapidly terminate life. Virtually all cell components are directly or indirectly affected by cellular iron metabolism, which represents a complex, redox-based machinery that is controlled by, and essential to, metabolic requirements. Under conditions of increased oxidative stress­i.e., enhanced formation of reactive oxygen species (ROS)­however, this machinery may turn into a potential threat, the continued requirement for iron promoting adverse reactions such as the iron/H2O2-based formation of hydroxyl radicals, which exacerbate the initial pro-oxidant condition. This review will discuss the multifaceted homeodynamics of cellular iron management under normal conditions as well as in the context of oxidative stress.

Frequency Distribution and Association of some Morpho- and Physiological Traits in Patients with Lung Diseases in Kosova.

The aim of this study was to investigate the distribution of specific phenotypes in patients with lung diseases as well as their eventual association with the risk of developing lung diseases. For this purpose 2777 patients with lung diseases and 2778 healthy individuals from all over Kosova were examined for the appearance of the following selected phenotypes: ear lobe free (ELF)/ear lobe attached, normal chin (NC)/cleft chin, tongue roller (TR)/non roller, hand clasping right thumb over (HC)/hand clasping left thumb over, righthanded (RH)/lefthanded. In addition, the blood group from ABO system and the presence or absence of the Rhesus factor asphenotypical markers were observed. The results obtained show significant differences between control and lung disease patients for NC (p ≤ 0.05) and TR (p ≤ 0.005) as well as for blood groups AB (p ≤ 0.05) and O (p ≤ 0.005). These results point to eventually increased levels of genetic load as a result of the increased homozygosity in some gene loci causing an increased frequency of some recessive phenotypes in patients with lung diseases. Together with the specific associations observed, these preliminary findings could serve as a basis for further in depth investigations with respect to the types of lung diseases, occupational exposure and dietary habits, and thus is expected to contribute to an understanding of predispositions and susceptibility to lung diseases.

Ferritin-stimulated lipid peroxidation, lysosomal leak, and macroautophagy promote lysosomal "metastability" in primary hepatocytes determining in vitro cell survival.

Several pathologies are associated with elevated levels of serum ferritin, for which growth inhibitory properties have been reported; however, the underlying mechanisms are still poorly defined. Previously we have described cytotoxic properties of isoferritins released from primary hepatocytes in vitro, which induce apoptosis in an iron and oxidative stress-dependent mode. Here we show that this ferritin species stimulates endosome clustering and giant endosome formation in primary hepatocytes accompanied by enhanced lysosomal membrane permeability (LMP). In parallel, protein modification by lipid peroxidation-derived 4-hydroxynonenal (HNE) is strongly promoted by ferritin, the HNE-modified proteins (HNE-P) showing remarkable aggregation. Emphasizing the prooxidant context, GSH is rapidly depleted and the GSH/GSSG ratio is substantially declining in ferritin-treated cells. Furthermore, ferritin triggers a transient upregulation of macroautophagy which is abolished by iron chelation and apparently supports HNE-P clearance. Macroautophagy inhibition by 3-methyladenine strongly amplifies ferritin cytotoxicity in a time- and concentration-dependent mode, suggesting an important role of macroautophagy on cellular responses to ferritin endocytosis. Moreover, pointing at an involvement of lysosomal proteolysis, ferritin cytotoxicity and lysosome fragility are aggravated by the protease inhibitor leupeptin. In contrast, EGF which suppresses ferritin-induced cell death attenuates ferritin-mediated LMP. In conclusion, we propose that HNE-P accumulation, lysosome dysfunction, and macroautophagy stimulated by ferritin endocytosis provoke lysosomal "metastability" in primary hepatocytes which permits cell survival as long as in- and extrinsic determinants (e.g., antioxidant availability, damage repair, EGF signaling) keep the degree of lysosomal destabilization below cell death-inducing thresholds.

Thymoquinone: an emerging natural drug with a wide range of medical applications.

Nigella sativa has attracted healers in ancient civilizations and researchers in recent times. Traditionally, it has been used in different forms to treat many diseases including asthma, hypertension, diabetes, inflammation, cough, bronchitis, headache, eczema, fever, dizziness and influenza. Experimentally, it has been demonstrated that N. sativa extracts and the main constituent of their volatile oil, thymoquinone, possess antioxidant, anti-inflammatory and hepatoprotective properties. In this review we aimed at summarizing the most recent investigations related to a few and most important effects of thymoquinone. It is concluded that thymoquinone has evidently proved its activity as hepatoprotective, anti-inflammatory, antioxidant, cytotoxic and anti-cancer chemical, with specific mechanisms of action, which provide support to consider this compound as an emerging drug. Further research is required to make thymoquinone a pharmaceutical preparation ready for clinical trials.

Pain and mobility improvement and MDA plasma levels in degenerative osteoarthritis, low back pain, and rheumatoid arthritis after infrared A-irradiation.

Infrared (IR)-A irradiation can be useful in back and musculoskeletal pain therapy. In this study joint and vertebral column pain and mobility were measured during two weeks of IR-A irradiation treatment of patients suffering from degenerative osteoarthritis of hip and knee, low back pain, or rheumatoid arthritis. Additionally, before and after IR-A treatment MDA serum levels were measured to check if MDA variations accompany changes in pain intensity and mobility. Two-hundred and seven patients were divided into verum groups getting IR-irradiation, placebo groups getting visible, but not IR irradiation, and groups getting no irradiation. In osteoarthritis significant pain reduction according to Visual Analogue Scale and mobility improvements occurred in the verum group. Even though beneficial mean value changes occurred in the placebo group, the improvements in the placebo and No Irradiation groups were without statistical significance. In low back pain, pain and mobility improvements (by 35-40%) in the verum group were found, too. A delayed (2nd week) mobility improvement in rheumatoid arthritis was seen. However, pain relief was seen immediately. In patients suffering from low back pain or rheumatoid arthritis, the pain and mobility improvements were accompanied by significant changes of MDA serum levels. However, MDA appears not a sensitive biofactor for changes of the pain intensity in degenerative osteoarthritis. Nevertheless, unaffected or lowered MDA levels during intensive IR-A therapy argue against previous reports on free radical formation upon infrared. In conclusion, rapid beneficial effects of IR-A towards musculoskeletal pain and joint mobility loss were demonstrated.

Cytotoxicity of ß-carotene cleavage products and its prevention by antioxidants.

When we investigated the genotoxicity of beta-carotene cleavage products (CPs) in primary rat hepatocytes stimulated to proliferate, we observed dose-dependent increases of chromosomal aberrations, sister chromatid exchanges and micronuclei. In contrast to other genotoxic substances, however, this increased genotoxicity was not accompanied by increased cytotoxicity. As a consequence we observed metaphases showing massive chromosomal damage, indicating inhibition of apoptosis by CPs enabling these cells to proceed in the cell cycle. Since proliferative stimulation by growth factors may support this effect, the in vitro toxicological effects of CPs were studied on proliferatively quiescent primary rat hepatocytes. A significant increase of both apoptosis and necrosis was found. Supplementation with antioxidants did not significantly lower the level of apoptosis, while the level of necrosis was significantly reduced by Trolox and N-acetylcysteine at all concentrations tested as well as ascorbic acid (50 microM) and a combination of Trolox (50 microM) and ascorbic acid (50 microM). These observations indicate that a) the cytotoxic potential in combination with the genotoxic potential of CPs may promote the initiation of cells due to compensatory cell division in exposed tissues and may aggravate inflammatory processes under chronic exposure, and b) the applied antioxidants may protect from cytotoxicity primarily via the detoxification of aldehydic beta-carotene cleavage products.

Iron-mediated oxidative stress plays an essential role in ferritin-induced cell death.

Previously, we have demonstrated an apoptosis-inducing activity of an acidic, H-chain-rich isoferritin secreted from primary rat hepatocytes in vitro. Because this proapoptotic property may be responsible for the growth-inhibitory and immunosuppressive effects described for certain ferritin species, we aimed to address the mechanism by which ferritin can trigger cell death. Suggesting a pivotal role for iron, iron chelation by desferrioxamine significantly abrogates ferritin-mediated apoptosis and necrosis in primary rat hepatocytes and substantially lowers the extent of protein modification by 4-hydroxynonenal (HNE)-a major lipid peroxidation (LPO) product. Furthermore, supplementing the cultures with the radical-scavenging compound trolox also provided significant protection from ferritin-mediated apoptosis. Moreover, a significant increase in micronucleated cells upon exposure to ferritin indicates that ferritin also introduces damage to DNA. Based on these observations we therefore propose that endocytosis of extracellular ferritin increases the level of free ferrous iron in the lysosomal compartment, promoting Fenton chemistry-based oxidative stress involving LPO and increased lysosomal membrane permeability. Subsequently, the release of reactive lysosomal content leads to cellular damage, in particular modification of protein and DNA induced by HNE and other reactive aldehydic LPO products. Together, these effects will trigger apoptosis and necrosis based on the upregulation of p53, increased mitochondrial membrane permeability, and proapoptotic Fas signaling as described recently. In conclusion, based on their iron-storing ability, secreted acidic isoferritins may act as soluble mediators of oxidative stress under certain physiological and pathophysiological conditions.

Evaluation of genotoxic and cytotoxic effects of H2O2 and DMNQ on freshly isolated rat hepatocytes; protective effects of carboxymethyl chitin-glucan.

OBJECTIVES: Utilizing primary rat hepatocytes we investigated the potential antimutagenic and anti-cytotoxic effects of carboxymethyl chitin-glucan (CM-CG) with respect to oxidative stress induced by the model free-radical-generating compounds hydrogen peroxide (H2O2) or 2,3-dimethoxy-1,4-naphthoquinone (DMNQ). Different kinds of CM-CG action were studied by two different treatment protocols: a. pre-incubation of freshly isolated hepatocytes with the potential anti-mutagen followed by exposure to the oxidant or b. simultaneous treatment of hepatocytes with the potential anti-mutagen and the oxidant. METHODS: As a measure of genotoxicity, the percentages of DNA in tails of comets by single cell gel electrophoresis were evaluated. The cytotoxicological endpoints analysed were the cell density (number of cells/cm2), and the percentages of apoptotic and necrotic cells. RESULTS: H2O2 and DMNQ, causing DNA single-strand breaks via the formation of *OH radicals, have been demostrated to induce both genotoxic and cytotoxic effects in primary rat hepatocytes resulting in increased percentages of DNA in tails of comets, and increased frequencies of apoptotic and necrotic cells accompanied by a decreased cell density. Further investigations were therefore focussed on possible modifications of these parameters by CM-CG. The results obtained clearly demonstrate that CM-CG (applied before and during treatment) protects primary rat hepatocytes against the genotoxic and cytotoxic effects of oxidative stress (H2O2 or DMNQ), whereas CM-CG itself has no effect on the endpoints of genotoxicity and cytotoxicity studied. CONCLUSION: Our results indicate that carboxymethyl chitin-glucan represents a natural fungal polysaccharide that can inhibit the genotoxicity and cytotoxicity of experimentally induced oxidative stress in primary rat hepatocytes.

Ferritin--a mediator of apoptosis?

Previously we have demonstrated an apoptosis inducing activity for a rat hepatocyte conditioned medium (CM) presumably mediated by acidic isoferritins. Here, we present support for this assumption since isoferritins purified from different rat hepatocyte CM significantly enhanced the frequency of apoptotic cells in primary rat hepatocytes, an effect completely inhibited by a neutralizing anti-H-ferritin antibody. The apoptosis induction appears to be related to a 43 kDa ferritin subunit contained in the isoferritins released from primary hepatocytes, presumably representing a ferritin heavy/light chain heterodimer. In addition, these isoferritins immunologically crossreact with antibodies raised against placental isoferritin p43-PLF (which also contains a 43 kDa ferritin subunit) and melanoma-derived H-chain ferritin, representing ferritin isoforms which reveal immunomodulatory properties. Furthermore, p53 and FasL are upregulated upon isoferritin treatment in a time dependent mode, and apoptosis induction can be suppressed by neutralizing anti-FasL antibodies. Proapoptotic Bid is upregulated too and translocated into mitochondria in primary hepatocytes exposed to the isoferritins purified from the CM. Finally, epidermal growth factor (EGF) and dexamethasone (DEX), which counteract proapoptotic mitochondrial signalling, almost completely abolished the proapoptotic effect of the hepatocyte derived isoferritins. In conclusion, our findings demonstrate that acidic isoferritins with homology to immunomodulatory ferritin isoforms (p43-PLF, melanoma-derived-H-chain ferritin) are released from hepatocytes in vitro, and are able to stimulate upregulation of p53 and mediate apoptosis involving Fas (CD95) signalling as well as addressing the intrinsic mitochondrial proapoptotic pathway.

Protective bystander effects simulated with the state-vector model.

Apoptosis induced in non-hit bystander cells is an important biological mechanism which operates after exposure to low doses of low-LET radiation. This process was implemented into a deterministic multistage model for in vitro neoplastic transformation: the State-Vector Model (SVM). The new model is tested on two data sets that show a reduction of the transformation frequency below the spontaneous level after exposure of the human hybrid cell line CGL1 to low doses of gamma-radiation. Stronger protective effects are visible in the data for delayed plating while the data for immediate plating show more of an LNT-like dose-response curve. It is shown that the model can describe both data sets. The calculation of the time-dependent numerical solution of the model also allows to obtain information about the time-dependence of the protective apoptosis-mediated process after low dose exposures. These findings are compared with experimental observations after high dose exposures.

Effect of oxidative stress on the junctional proteins of cultured cerebral endothelial cells.

(1) There is increasing evidence that the cerebral endothelium and the blood-brain barrier (BBB) plays an important role in the oxidative stress-induced brain damage. The aim of the present study was to investigate the role of interendothelial junctional proteins in the BBB permeability increase induced by oxidative stress. (2) For the experiments, we have used cultured cerebral endothelial cells exposed to hypoxia/reoxygenation or treated with the redox cycling quinone 2,3-Dimethoxy-1,4-naphthoquinone (DMNQ) in the presence or absence of glucose. The expression of junctional proteins and activation of mitogen activated protein kinases (MAPK) was followed by Western-blotting, the interaction of junctional proteins was investigated using coimmunoprecipitation. (3) Oxidative stress induces a downregulation of the tight junction protein occludin expression which is more pronounced in the absence of glucose. Furthermore, oxidative stress leads to disruption of the cadherin-beta-catenin complex and an activation of extracellular signal-regulated kinase (ERK1/2), which is more intense in the absence of glucose. (4) We have shown that one of the causes of the BBB breakdown is probably the structural alteration of the junctional complex caused by oxidative stress, a process in which ERK1/2 may play an important role.

Genotoxicity of HNE.

Since previous investigations on the genotoxicity of 4-hydroxynonenal (HNE) were carried out with prokaryotic systems or eukaryotic cell lines which may not adequately reflect the response of cells in vivo due to differences in the metabolism, the genotoxic potential of HNE was further evaluated in primary cells (hepatocytes) and cell clones of cerebral endothelial cells expressing specific functions, i.e. blood-brain barrier (BBB) and capillary formation associated phenotypes. Treatment of hepatocytes with HNE induced statistically significant levels of SCE at concentrations >/=0.1 microM, micronuclei at concentrations >/=1 microM and chromosomal aberrations at a concentration of 10 microM. Treatment of cloned cerebral microvascular endothelial cells induced significantly elevated levels of chromosomal aberrations at concentrations >/=1 microM and micronuclei at concentrations >/=10 microM in both cEC phenotypes, compared to the controls. Additionally, cytotoxicity was observed at a concentration of 50 microM HNE and was significantly higher in type II cells. These results indicate that cells expressing differentiated functions representative for the in vivo situation react more sensitive to HNE than cell lines, and may reflect the sensitivity of the target cells. The different response with respect to the endpoints of genotoxicity tested most probably depends on the different metabolizing capacities and thus the action of different metabolites of HNE.