Satisfaction with information about ionising radiation: a comparative study in Belgium and France.

In recent decades efforts have been made to meet societal expectations concerning public access to information and to enable citizens' informed decision-making related to ionising radiation risks. But are people satisfied with the information provided and which factors influence this? This paper investigates lay persons' satisfaction with the information about ionising radiation provided by different communicators in Belgium and France. In particular, it studies the potential influence of risk perception, confidence in authorities, knowledge and education. The study is based on data originating from large scale public opinion surveys (N = 1002 in Belgium; N = 966 in France). Results show that the two countries differ as regards satisfaction with the information provided by specific communicators. Confidence in authorities was revealed in both countries as more important for satisfaction with information than risk perception. Contrary to expectations, general knowledge about ionising radiation had limited or no explanatory power. An additional study for the Belgian sample showed that both perceived trustworthiness and technical competence influence satisfaction with information, but their relative importance depends on the communicator.

Clinical impact of hyperattenuation of adrenal glands on contrast-enhanced computed tomography of polytraumatised patients.

OBJECTIVE: To evaluate the prognostic value of hyperattenuating adrenal glands on contrast-enhanced CT of polytraumatised patients. METHODS: Two hundred ninety-two patients (195 men and 97 women, mean age 45.3 ± 23.3 years) were included in this retrospective study. CT examinations were performed 60 s after intravenous injection of contrast material. Image analysis was performed by two radiologists. Patients were assigned to one of two groups according to the attenuation of the adrenal gland [group 1: adrenal glands ≥ inferior vena cava (IVC); group 2: adrenal glands < IVC]. RESULTS: Eighteen patients (42.2 years ± 24.2) were assigned to group 1 and 274 patients (48.4 years ± 22.4) to group 2. The average adrenal density was 150.8 ± 36.1 HU in group 1 and 83.7 ± 23.6 HU in group 2 (P < 0.0001). Eight of the 18 patients in group 1 (44.4%) and 33 of the 274 patients in group 2 (12.4%) died during hospitalisation (P < 0.05). Mean adrenal enhancement was significantly higher in patients who died (101.9 ± 40.6 HU) compared with survivors (86.1 ± 27.0 HU; P < 0.001). CONCLUSION: Hyperattenuation of adrenal glands is associated with a higher mortality rate in polytraumatised patients and may serve as a predictor of poor clinical outcome. KEY POINTS: • Hyperattenuating adrenal glands can be observed in 6.2% of polytraumatised patients. • Hyperattenuating adrenal glands indicate poor clinical outcome in polytraumatised patients. • In polytraumatised patients, hyperattenuating adrenal glands are associated with a high mortality rate. • Adrenal enhancement is higher amongst patients who died than amongst survivors.

PON3 is upregulated in cancer tissues and protects against mitochondrial superoxide-mediated cell death.

To achieve malignancy, cancer cells convert numerous signaling pathways, with evasion from cell death being a characteristic hallmark. The cell death machinery represents an anti-cancer target demanding constant identification of tumor-specific signaling molecules. Control of mitochondrial radical formation, particularly superoxide interconnects cell death signals with appropriate mechanistic execution. Superoxide is potentially damaging, but also triggers mitochondrial cytochrome c release. While paraoxonase (PON) enzymes are known to protect against cardiovascular diseases, recent data revealed that PON2 attenuated mitochondrial radical formation and execution of cell death. Another family member, PON3, is poorly investigated. Using various cell culture systems and knockout mice, here we addressed its potential role in cancer. PON3 is found overexpressed in various human tumors and diminishes mitochondrial superoxide formation. It directly interacts with coenzyme Q10 and presumably acts by sequestering ubisemiquinone, leading to enhanced cell death resistance. Localized to the endoplasmic reticulum (ER) and mitochondria, PON3 abrogates apoptosis in response to DNA damage or intrinsic but not extrinsic stimulation. Moreover, PON3 impaired ER stress-induced apoptotic MAPK signaling and CHOP induction. Therefore, our study reveals the mechanism underlying PON3's anti-oxidative effect and demonstrates a previously unanticipated function in tumor cell development. We suggest PONs represent a novel class of enzymes crucially controlling mitochondrial radical generation and cell death.

[Interhospital transfer of severely injured patients in Germany. Evaluation of the DGU trauma register]. / Verlegungsrealität schwerverletzter Patienten in Deutschland. Eine Auswertung im TraumaRegister DGU.

BACKGROUND: The TraumaNetzwerk(D) DGU was founded 3 years ago and since then the majority of trauma centers have been registered and organized into regional trauma network services (TNW). Within these networks assessment criteria for transferring patients to higher level hospitals are defined. The purpose of this study was to evaluate the incidence, causes, implications and quality of care for patients with major trauma who were transferred for definitive treatment before implementation of the TraumaNetzwerk(D) DGU in Germany. PATIENT AND METHODS: The data of 19,035 patients listed in the German Trauma Register of the German Society for Trauma Surgery (DGU, 2002-2007) were analyzed. Patients with an injury severity score (ISS) >9 and a blood pressure documented on admission were included into the study. Data were allocated according to patients where therapy was performed completely in the primary hospital of admission (group I; n=16,033; 84.2%) and patients transferred after primary care from one hospital to another centre for definitive care (group II; n=3,002; 15.8%). Comparative parameters were the pattern and severity of injury, physiological state on admission and clinical outcome. RESULTS: Mean ISS and percentage of patients with an ISS ≥25 did not differ significantly between groups. Of the patients who were transferred to a higher level trauma centre (group II) 20.7% needed catecholamines on admission, 10.1% were in shock (blood pressure <90 mmHg) and 2.5% of the patients underwent resuscitation in the emergency department. Patients of group II had a considerably longer hospital stay (31.2±35.5 days) than patients of group I (24.8±27.1 days). Furthermore, treatment costs were significantly higher for group II (I: EUR 23,870; II: EUR 26,054). CONCLUSIONS: A relevant percentage of patients transferred from one hospital to another were hemodynamically and clinically unstable. To what extent the quality of patient transfer and therefore major trauma care is improved by the implementation of regional trauma networks in Germany remains to be seen over the next years.

Beyond reduction of atherosclerosis: PON2 provides apoptosis resistance and stabilizes tumor cells.

Major contributors to atherosclerosis are oxidative damage and endoplasmic reticulum (ER) stress-induced apoptosis; both of which can be diminished by the anti-oxidative protein paraoxonase-2 (PON2). ER stress is also relevant to cancer and associated with anti-cancer treatment resistance. Hence, we addressed, for the first time, whether PON2 contributes to tumorigenesis and apoptotic escape. Intriguingly, we found that several human tumors upregulated PON2 and such overexpression provided resistance to different chemotherapeutics (imatinib, doxorubicine, staurosporine, or actinomycin) in cell culture models. This was reversed after PON2 knock-down. Remarkably, just deficiency of PON2 caused apoptosis of selective tumor cells per se, demonstrating a previously unanticipated oncogenic function. We found a dual mechanistic role. During ER stress, high PON2 levels lowered redox-triggered induction of pro-apoptotic CHOP particularly via the JNK pathway, which prevented mitochondrial cell death signaling. Apart from CHOP, PON2 also diminished intrinsic apoptosis as it prevented mitochondrial superoxide formation, cardiolipin peroxidation, cytochrome c release, and caspase activation. Ligand-stimulated apoptosis by TRAIL or TNFα remained unchanged. Finally, PON2 knock-down caused vast reactive oxygen species formation and stimulated JNK-triggered CHOP expression, but inhibition of JNK signaling did not prevent cell death, demonstrating the pleiotropic, dominating anti-oxidative effect of PON2. Therefore, targeting redox balance is powerful to induce selective tumor cell death and proposes PON2 as new putative anti-tumor candidate.

[Interruption of the diagnostic algorithm and immediate surgical intervention after major trauma--incidence and clinical relevance. Analysis of the Trauma Register of the German Society for Trauma Surgery]. / Abbruch der Schockraumdiagnostik und Notfalloperation beim Polytrauma--Inzidenz und klinische Relevanz. Eine Auswertung des TraumaRegisters der DGU.

BACKGROUND: Life-threatening situations after multiple trauma which require interruption of the diagnostic algorithm and immediate surgical treatment after admission are a challenge for the multidisciplinary trauma team. The purpose of this study was to evaluate the incidence, causes, implications and relevance of life-threatening situations for major trauma patients after admission to trauma centers. PATIENT AND METHODS: Data of 12,971 patients listed in the German Trauma Register of the German Society for Trauma Surgery (DGU, 2002-2007) were analyzed. Patients with an injury severity score (ISS) > 16, no isolated head injury and primary admission to a trauma center were included. Data were allocated according to patients where the diagnostic algorithm in the resuscitation room was interrupted to perform emergency surgery (group Notop, n = 713, 5.5%) and patients who received early surgical care after completed diagnostics (group Frühop, n = 5,515, 42.5%). Comparative parameters were the pattern and severity of injury, physiological state and clinical outcome. RESULTS: Patients receiving emergency surgery showed an average ISS score of 39 ± 15 points, whereas patients receiving early surgery showed an average ISS of 31 ± 12 points. On admission patients in the emergency surgery group (44%) suffered from hemodynamic shock considerably more often than patients in the early surgery care group (15%, p < 0.001). This was indicated by the significant differences in systolic blood pressure on admission, amount of preclinical substituted volume, base excess on admission and substituted erythrocyte concentrates in early clinical course. Mortality was 46% in the emergency surgery group and 13% in the early surgical care group (p < 0.001). Severe injuries (AIS ≥ 4) of the thorax, abdomen and extremities (including the pelvis) were encountered considerably more often in the emergency surgery group. There was no statistical difference in occurrence of severe head injuries between the groups. Emergency surgery consisted of 50.5% laparatomy, 19.8% craniotomy, 10.0% thoracotomy and 9.3% pelvic surgery. CONCLUSION: Life-threatening situations after major trauma which require immediate surgical intervention in the resuscitation room rarely occur in Germany. Nevertheless, they are associated with a high mortality and prolonged and complex clinical course if primarily survived. Indications and decision-making processes of these challenging situations have to be practiced with standardized algorithms and should be considered for the future education of orthopedic surgeons in Germany.

Automated analysis of DNA damage in the high-throughput version of the comet assay.

Recently a high-throughput version of the comet assay was developed using a special 96-well multichamber plate (MCP) [1]. In this version, the electrophoresis is performed directly on the MCP, which makes transferring of cells to microscope slides unnecessary. In order to facilitate the scoring procedure we adapted an automated slide-scanning system (Metafer MetaCyte with CometScan) to enable unattended analysis of comets on the MCP. The results of the system were compared with the data obtained with two interactive comet-assay analysis systems. For induction of DNA damage in human fibroblasts methylmethane sulfonate (MMS) or H2O2 was used. The three systems revealed similar, concentration-dependent results for all parameters tested: tail moment (tm), % DNA-in-tail and olive tail moment. Near the detection limit of 5-6% DNA-in-tail a significant difference with the untreated control was obtained by use of four parallel samples (p=0.01). With the newly developed automated analysis system, the evaluation of either 50 or 100 comets yielded similar standard errors for either treatment with MMS or H2O2, thus showing that the method is suitable to reveal the crucial low-dose effects with high precision. The results also show that the time needed for automated evaluation of comets on the MCP was reduced by a factor of 10 when compared with the time required for interactive evaluation. In summary, the high-throughput version of the comet assay combined with the automated evaluating system increased the output by a factor up to 180 compared with the standard method.

Performance of the comet assay in a high-throughput version.

The high-throughput comet assay was developed to reduce the processing time and to increase sample-throughput of the assay as described by Tice et al. (RR. Tice, E. Agurell, D. Anderson, B. Burlinson, A. Hartmann, H. Kobayashi, Y. Miyamae, E. Rojas, JC. Ryu, YF. Sasaki. Single cell gel/comet assay: guidelines for in vitro and in vivo genetic toxicology testing, Environ. Mol. Mutagen.35 (2000) 206-221). This high-throughput version allows for the processing of up to 400 samples per day. The basis of the new assay is a 96-well plate (multichamber plate, MCP) suitable for electrophoresis. After exposure of the cells to genotoxic agents, the walls of the MCP are separated from the bottom plate. All 96 samples together then go through lysis, alkaline unwinding, electrophoresis, neutralization, and staining. In this study, the first concentration-dependent results obtained with the high-throughput version are shown and a comparison is made with the standard version of the comet assay using five representative chemicals with different genotoxic properties. These genotoxic chemicals are methyl methanesulfonate (MMS) and ethylnitrosourea, which form small alkylation adducts, 4-nitroquinoline-1-oxide for bulky adducts, cisplatin for DNA cross-links, and H(2)O(2) for direct DNA breakage. For medium and high effective concentrations a standard deviation of 3-20% for three replicates (25 comets per sample) was determined. A comparison of the standard assay with the high-throughput version revealed similar results for MMS and H(2)O(2). The integrated viability assay (FDA assay), which was performed after chemical treatment and before detachment of the bottom from the walls of the MCP, did not influence the outcome of the comet formation. In conclusion, the high-throughput version of the comet assay facilitates the determination of genotoxicity in cases where large numbers of samples have to be measured, such as during testing of industrial chemicals, biomonitoring of environmental samples, and early screening of drug candidates for genotoxicity/photogenotoxicity. For such applications the cost- and time-saving of the high-throughput method provides substantial advantages over the standard comet assay.

Multistep loading of titania nanoparticles in the mesopores of SBA-15 for enhanced photocatalytic activity.

A multistep deposition of anatase nanoparticles was employed to incorporate high amounts of titania into the mesopores of SBA-15. Anatase nanoparticles were synthesized and deposited following the Acid Catalyzed Sol Gel method. With this method, the size of the anatase nanoparticles can be controlled and therefore, the titania loading into the mesopores of SBA-15 can be controlled. Through multistep deposition of anatase nanoparticles, a further increase of titania loading into the mesoporous channels can be obtained. For the degradation of Rhodamine-6G, the samples synthesized by multistep deposition showed an enhanced photocatalytic activity.

Synergistic DNA damage by oxidative stress (induced by H2O2) and nongenotoxic environmental chemicals in human fibroblasts.

Genotoxic combination effects of oxidative stress (induced by H2O2) and eight nongenotoxic environmental chemicals (4-chloroaniline, 2,3,4,6-tetrachlorophenol, lindane, 2,4-dichloroacetic acid (2,4-D), m-xylene, glyphosate, nitrilotriacetic acid and n-hexanol) were determined in human fibroblasts. Genotoxicity was measured quantitatively by the single cell gel electrophoresis assay. The nongenotoxic chemicals were used in non cytotoxic concentrations. H2O2 was used in concentrations producing low (50 microM) and no cytotoxicity (40 microM). All environmental chemicals acted in a synergistic way with H2O2 except DMSO which effectively inhibited H2O(2)-induced DNA damage. The most effective enhancers were 4-chloroaniline, 2,3,4,6-tetrachlorophenol, m-xylene, and n-hexanol. Synergistic effects of hexanol/H2O2 were still evident at a concentration of 0.09 noec (no observed effect concentration). In contrast to synergistic DNA damage in the cell antagonism was found measuring DNA breakage in isolated PM2 DNA. From the results we concluded that synergisms between H2O2 and nongenotoxic chemicals may be a general phenomenon which is not observed on the level of isolated DNA.

Synergistic DNA damaging effects of 4-nitroquinoline-1-oxide and non-effective concentrations of methyl methanesulfonate in human fibroblasts.

DNA damage and DNA repair in human fibroblasts induced by the combination mixture of the genotoxic agents methyl methanesulfonate (MMS) and 4-nitroquinoline-1-oxide (4-NQO) were studied using the comet assay and the unscheduled DNA synthesis (UDS), respectively. Cells were simultaneously treated for 1h with the no observed effect concentration (noec) of MMS and increasing concentrations of 4-NQO or vice versa. Different results were obtained with the two types of mixtures. When the noec of 4-NQO was combined with increasing concentrations of MMS, no combination effects were observed. However, in experiments with increasing concentrations of 4-NQO and the noec of MMS, an increase in DNA damage and repair (and an enhancement of cytotoxicity) was demonstrated. Quantitative analysis of the effects by the isobologram method confirmed synergistic responses in both tests. We are proposing interactive actions between 4-NQO and MMS, whereby 4-NQO facilitates the attack of MMS on the DNA bases.

Protection by desferrioxamine and other hydroxamic acids against tetrachlorohydroquinone-induced cyto- and genotoxicity in human fibroblasts.

Tetrachlorohydroquinone (TCHQ) has been identified as a major toxic metabolite of the widely used wood preservative pentachlorophenol and has also been implicated in its genotoxicity. We have recently demonstrated that protection by the trihydroxamate iron chelator desferrioxamine (DFO) on TCHQ-induced single-strand breaks in isolated DNA was not the result of its chelation of iron but rather of its efficient scavenging of the reactive tetrachlorosemiquinone (TCSQ) radical. In this study, we extended our research from isolated DNA to human fibroblasts. We found that DFO provided marked protection against both the cyto- and genotoxicity induced by TCHQ in human fibroblasts when it was incubated simultaneously with TCHQ. Pretreatment of the cells with DFO followed by washing also provided marked protection, although less efficiently compared with the simultaneous treatment. Similar patterns of protection were also observed for three other hydroxamic acids (HAs): aceto-, benzo-, and salicylhydroxamic acid. Dimethyl sulfoxide, an efficient hydroxyl radical scavenger, provided only partial protection even at high concentrations. In vitro studies showed that the HAs tested effectively scavenged the reactive TCSQ radical and enhanced the formation of the less reactive and less toxic 2,5-dichloro-3, 6-dihydroxy-1,4-benzoquinone (chloranilic acid). The results of this study demonstrated that the protection provided by DFO and other HAs against TCHQ-induced cyto- and genotoxicity in human fibroblasts is mainly through scavenging of the observed reactive TCSQ radical and not through prevention of the Fenton reaction by the binding of iron in a redox-inactive form.

Induction of lipid peroxidation in human fibroblasts by the antioxidant propyl gallate in combination with copper(II).

The antioxidant propyl gallate (PG) induced lipid peroxidation in combination with non-toxic Cu(II) concentrations in human fibroblasts. This was measured by the thiobarbituric acid assay (TBA assay) and by detection of accumulating fluorescent products after a 1-h treatment of cells with CuCl2/PG at concentrations higher than 0.125 mM. PG alone led to a significant reduction of thiobarbituric acid-reactive substances (TBARS) demonstrating its antioxidative properties. Time course studies of lipid peroxidation by PG/Cu(II) showed that formation of TBARS was preceded by a lag phase of 60 min. Thereafter, the TBARS value increased rapidly for 1 h and then reached a constant maximum or slightly decreased. The induction of lipid peroxidation by PG/Cu(II) is probably due to the formation of reactive species like reactive oxygen species (ROS), Cu(I) and semiquinone radicals which are able to participate in initiation and propagation of lipid peroxidation. Combination effects of PG/Cu(II) were demonstrated also on inhibition of membrane-bound succinate dehydrogenase. Cytosolic esterases were affected only slightly. The greater susceptibility of membrane-bound enzymes is in accordance with the lipid peroxidation-inducing effects of PG/Cu(II).

Different DNA damaging species as a result of oxidation of n-butyraldehyde and iso-butyraldehyde by Cu(II).

The isomers n- and iso-butyraldehyde (BuA) in combination with Cu(II) induced single and double strand breaks in PM2 DNA, whereas the aldehydes, or Cu(II) alone had only negligible effect. The DNA damage was the result of radical oxidations of the aldehydes under formation of Cu(I). Cu(I) formation was independent of molecular oxygen. Extensive DNA degradation was only observed in the presence of molecular oxygen. Characterization of DNA damage pointed to different ultimate DNA damaging species. While catalase and neocuproine inhibited strand break formation induced by iso-BuA/Cu(II) to a high degree, these inhibitors were less effective in the n-BuA/Cu(II) reaction. On the other hand, sodium azide showed a high strand break inhibition in the n-BuA/Cu(II) reaction, but low inhibition in the iso-BuA/Cu(II) reaction. 2-Deoxyguanosine was hydroxylated in the 8-position by iso-BuA/Cu(II) but little reaction occurred with n-BuA/Cu(II). Chemiluminescence was detected during both BuA/Cu(II) reactions, whereby the intensity of the luminescence signal was 3.5-fold higher for n-BuA/Cu(II) than for iso-BuA/Cu(II). We suppose that the copper(II)-driven oxidation of n- and iso-BuA proceeds via different pathways with different DNA damaging consequences. Whereas the oxidation of iso-BuA mainly results in damage by .OH-radicals, the oxidation of n-BuA may lead to a radical reaction chain whereby excited states are involved and the resulting DNA-damaging species are not .OH-radicals.

Cytotoxicity and mutagenicity of a 2,4,6-trinitrotoluene (TNT) and hexogen contaminated soil in S. typhimurium and mammalian cells.

The toxicity and mutagenicity of aqueous and organic extracts of soil contaminated with TNT, TNT metabolites and hexogen was determined in mammalian cell lines and in prokaryotic cells. The prokaryotic toxicity was determined via the colony forming ability of Salmonella typhimurium (strains TA 98 and TA 100). The same strains were used to test mutagenicity in the Ames test. The mammalian toxicity was analyzed in human fibroblasts by the inhibition of cell growth and cell viability (MTT assay). The mammalian mutagenicity was tested with the HPRT test in V79 cells (hamster lung). The aqueous soil extract did not reveal toxicity or mutagenicity in any of the tests performed. The DMSO/ethanol extract showed toxicity and mutagenicity in S. typhimurium. Thereby strain TA 98 was more sensitive than strain TA 100. In human fibroblasts cell growth was strongly inhibited, whereas no reduction of cell viability was found in the MTT test. Mutagenicity of the DMSO/ethanol extract of the soil was demonstrated in V79 cells.

DNA strand break induction and enhanced cytotoxicity of propyl gallate in the presence of copper(II).

The antioxidant propyl gallate (PG) induced single strand breaks in PM2 DNA at concentrations higher than 0.25 microM when it was combined with copper concentrations at 5 microM and above. In combination with 100 microM CuCl2, extensive double strand breakage was also observed. Neither PG alone nor CuCl2 showed any strand breaking properties. DNA strand breakage was inhibited by addition of catalase or the Cu(I) chelator neocuproine, indicating the involvement of H2O2 and a Cu(II)/Cu(I) redox cycle in the DNA damage. DNA damage of PG/Cu(II) was also observed in human fibroblasts. Using the alkaline elution technique concentrations of 0.15-0.5 mM PG induced DNA strand breaks in combination with 2.5 mM CuCl2, while the single substances did not show any effect. At these concentrations cell viability measured by the MTT assay was not reduced by more than 10%; however, cell growth was inhibited by PG in combination with Cu(II). This growth inhibition was apparently due to the DNA damage incurred by PG/Cu(II). The synergistic interaction between PG and Cu(II) is probably caused by a redox reaction between both compounds, whereby reactive species such as ROS are formed, which are responsible for the observed genotoxic and cytotoxic effects. Our results demonstrate that the antioxidative and cytoprotective properties of propyl gallate may change to prooxidative, cytotoxic and genotoxic properties in the presence of Cu(II).

Synergistic DNA damaging effects of malondialdehyde/Cu(II) in PM2 DNA and in human fibroblasts.

Malondialdehyde (MDA) is a product of lipid peroxidation (LPO). In combination with CuCl2 MDA induced single strand breaks in PM2 DNA whereas MDA or CuCl2 alone had no effect. Cu(II) oxidized MDA by a radical mechanism under formation of Cu(I). DNA strand break induction was inhibited by catalase (98%), neocuproine (76%) and DMSO (61%). The synergistic damaging effect of MDA and Cu(II) was also demonstrated in human fibroblasts measured by alkaline elution. The combination MDA/CuCl2 caused extensive DNA breakage while neither MDA nor CuCl2 alone induced DNA damage within the cell. Synergistic cytotoxic effects were observed 18 h after a simultaneous treatment of the cells with MDA and CuCl2 for 1 h.

AFLP Linkage Map of the Oomycete Phytophthora infestans

Here we present the first comprehensive genetic linkage map of the heterothallic oomycetous plant pathogen Phytophthora infestans. The map is based on polymorphic DNA markers generated by the DNA fingerprinting technique AFLP (Vos et al., 1995, Nucleic Acids Res. 23: 4407-4414). AFLP fingerprints were made from single zoospore progeny and 73 F1 progeny from two field isolates of P. infestans. The parental isolates appeared to be homokaryotic and diploid, their AFLP patterns were mitotically stable, and segregation ratios in the F1 progeny were largely Mendelian. In addition to 183 AFLP markers, 7 RFLP markers and the mating type locus were mapped. The linkage map comprises 10 major and 7 minor linkage groups covering a total of 827 cM. The major linkage groups are composed of markers derived from both parents, whereas the minor linkage groups contain markers from either the A1 or the A2 mating type parent. Non-Mendelian segregation ratios were found for the mating type locus and for 13 AFLP markers, all of which are located on the same linkage group as the mating type locus. Copyright 1997 Academic Press

Suitability of different cytotoxicity assays for screening combination effects of environmental chemicals in human fibroblasts.

Cytotoxicity screening assays measuring survival, growth, colony forming ability, DNA and protein synthesis in human fibroblasts were tested for their suitability to determine combination effects. Thereby, the dose-response curves of a hydrophilic substance A alone and after pretreatment with a membrane damaging substance B were compared. Substances B were applied at concentrations which did not induce toxic effects in the assays (noec). Synergistic combination effects were demonstrated by reduction of the EC20 value of substances A in the combination in comparison to substances A alone. The following substance pairs (substance B/substance A = membrane damaging/hydrophilic) were tested: n-dodecylbenzenesulfonic acid/2,4-dichlorophenoxyacetic acid, 2,4,6-trichlorophenol/2,4-dichlorophenoxyacetic acid, 1,1,2,2-tetrachloroethane/4-chloroaniline, pentachlorophenol/CrCl3. While survival, growth, and DNA synthesis assays were suitable methods for detecting synergistic combination effects, the growth assay was the most sensitive. Here, all four substance pairs showed synergistic combination effects.