Comet Percentage Research Articles

Preclinical study of genuine essiac formula: A cancer treatment eight-herbs' tea minimizes DNA insult of X-rays

Context: Essiac tea is been used widely in the homeopathy market for cancer treatment. Aims: We hypothesized its use for DNA-damaged mitigation under very low ionizing radiation (IR) on BALB/c mice (10–40 mSv). Settings and Design: The radioprotection of Essiac tea formulae was evidenced by comet assay (CA) and micronucleus (MN) acridine orange staining. We also reported complete blood count, animal weight, and fasting glucose levels to control for tea toxicity. Materials and Methods: Fifty BALB/c male mice of 6-7 week old and pathogen free mice were randomly divided in to control group, control irradiated mice, irradiated and tea or ascorbic acid treated mice, tea treated mice and ascorbic acid treated mice. Genuine Essiac tea treatment was given ad libitum for 7 weeks and ascorbic for no >13 days. The animals were exposed to three different X-ray doses (10 mSv, 20 mSv, and 40 mSv). Statistical Analysis Used: An independent one-tailed t-test or Dunnett's test was used to compare animal weight, fasting glucose levels, white blood count, comet percentage, and MN percentage, between doses, treatment, and controls, after a Welch's ANOVA and Mann–Whitney U-test using Excel worksheets from Biostathandbook.com website. Results: The tea formula resulted in a significant reduction of DNA damaged evidenced by CA (P

Activity-Dependent Nucleation of Dynamic Microtubules at Presynaptic Boutons Controls Neurotransmission.

Control of microtubule (MT) nucleation and dynamics is critical for neuronal function. Whether MT nucleation is regulated at presynaptic boutons and influences overall presynaptic activity remains unknown. By visualizing MT plus-end dynamics at individual excitatory en passant boutons in axons of cultured hippocampal neurons and in hippocampal slices expressing EB3-EGFP and vGlut1-mCherry, we found that dynamic MTs preferentially grow from presynaptic boutons, show biased directionality in that they are almost always oriented toward the distal tip of the axon, and can be induced by neuronal activity. Silencing of γ-tubulin expression reduced presynaptic MT nucleation, and depletion of either HAUS1 or HAUS7-augmin subunits increased the percentage of retrograde comets initiated at boutons, indicating that γ-tubulin and augmin are required for activity-dependent de novo nucleation of uniformly distally oriented dynamic MTs. We analyzed the dynamics of a wide range of axonal organelles as well as synaptic vesicles (SVs) relative to vGlut1+ stable presynaptic boutons in a time window during which MT nucleation at boutons is promoted upon induction of neuronal activity, and we found that γ-tubulin-dependent presynaptic MT nucleation controls bidirectional (SV) interbouton transport and regulates evoked SV exocytosis. Hence, en passant boutons act as hotspots for activity-dependent de novo MT nucleation, which controls neurotransmission by providing dynamic tracks for bidirectional delivery of SVs between sites of neurotransmitter release.

Discovery statistics and 1/a distribution of long-period comets detected during 1801–2017

For the last two decades we have been observing a huge increase in discoveries of long-period comets (LPCs), especially those with large-perihelion distances. We collected data for a full sample of LPCs discovered over the 1801-2017 period including their osculating orbits, discovery moments (to study the discovery distances), and original semimajor axes (to study the number ratio of large-perihelion to small-perihelion LPCs in function of 1/a-original, and to construct the precise distribution of an 1/a-original). To minimize the influence of parabolic comets on these distributions we determined definitive orbits (which include eccentricities) for more than 20 LPCs previously classified as parabolic comets. We show that the percentage of large-perihelion comets is significantly higher within Oort spike comets than in a group of LPCs with a<10000 au, and this ratio of large-perihelion to small-perihelion comets for both groups has grown systematically since 1970. The different shape of the Oort spike for small-perihelion and large-perihelion LPCs is also discussed. A spectacular decrease of the ratio of large-perihelion to small-perihelion LPCs with the shortening of semimajor axis within the range of 5000-100 au is also noticed. Analysing discovery circumstances, we found that Oort spike comets are discovered statistically at larger geocentric and heliocentric distances than the remaining LPCs. This difference in the percentage of large-perihelion comets in both groups of LPCs can probably be a direct consequence of a well-known comets fading process due to ageing of their surface during the consecutive perihelion passages and/or reflects the different actual q-distributions.

Shape evolution of cometary nuclei via anisotropic mass loss

Context.Breathtaking imagery recorded during the European Space Agency Rosetta mission confirmed the bilobate nature of the nucleus of comet 67P/Churyumov-Gerasimenko. The peculiar appearance of the nucleus is not unique among comets. The majority of cometary cores imaged at high resolution exhibit a similar build. Various theories have been brought forward as to how cometary nuclei attain such peculiar shapes.Aims.We illustrate that anisotropic mass loss and local collapse of subsurface structures caused by non-uniform exposure of the nucleus to solar irradiation can transform initially spherical comet cores into bilobed cores.Methods.We derived a mathematical framework to describe the changes in morphology resulting from non-uniform insolation during the spin-orbit evolution of a nucleus. We solved the resulting partial differential equations that govern the change in the shape of a nucleus subject to mass loss and consequent collapse of depleted subsurface structures analytically for simple insolation configurations and numerically for more realistic scenarios.Results.The proposed mechanism is capable of explaining why a large percentage of periodic comets appear to have peanut-shaped cores and why light-curve amplitudes of comet nuclei are on average larger than those of typical main belt asteroids of the same size.

Sperm DNA damage output parameters measured by the alkaline Comet assay and their importance.

The alkaline Comet assay has shown high diagnostic value to determine male reproductive health and prognostic ability to predict ART success. Here, spermatozoon was analysed in 47 fertile donors and 238 patients, including 132 couples undergoing ART [semen was collected: Group I - within 3months of their treatment (n=79); and Group II - 3months prior to their treatment (n=53)]. We introduce four Comet distribution plots (A, B1, B2 and C) by plotting the level of DNA damage (x-axis) and percentage of comets (y-axis). Fertile donors had low mean DNA damage, olive tail moment and per cent of spermatozoa with damage and increased type A plots. Comet parameters were associated with clinical pregnancies in Group I. About 66% of couples with type A distribution plot were successful after ART, whereas couples with type B1, B2 and C distribution plots achieved 56%, 44% and 33% pregnancies respectively. The efficiency of the Comet assay was due to complete decondensation process, where the compact sperm nuclear DNA (28.2±0.2μm3 ) is decondensed to ~63μm3 (before lysis) and ~1018μm3 (after lysis). A combinational analysis of all the Comet output parameters may provide a comprehensive evaluation of patient's reproductive health as theseparameters measure different aspects of DNA damage within the spermatozoa.

Detection of DNA damage in sonochemotherapy against cisplatin-resistant human ovarian cancer cells using the modified comet assay

Purpose: To explore methodological modifications in the detection of DNA damage in sonochemotherapy for cisplatin-resistant human ovarian cancer cells using the comet assays.Materials and methods: Chemoresistant cells COC1/DDP were subjected to sonochemotherapy and DNA damage detected with the alkaline and neutral comet assays.Results: In the alkaline assay, the percentage of comets formed was less than that of dead cells, and most values for the percentage of comets formed were < 5% when using the default value to identify comets, showing an underestimation. These values were corrected when adjusting the threshold to the 95th percentile in control cells. In the neutral assay, this modification was not needed. Tail length (TL), tail moment (TM) and Olive tail moment (OTM) dramatically varied between comets. The 75th percentiles of TL, TM and OTM in the alkaline assay, and 90th percentiles in the neutral assay, correlated with the percentage of comets formed, thereby reflecting the temporal shift in DNA damage. Quantification of the interaction using the percentage of comets formed was consistent with that using the percentage of dead cells.Conclusions: The percentage of comets formed can be used to assess DNA damage in sonochemotherapy against chemoresistant cells when adjusting the threshold.

Biochemical, Immunological, DNA and Histopathological Changes Caused by Cannabis Sativa in the Rat

The aim of this study was to investigate the effect of repeated administration of Cannabis sativa extract on some biochemical, immunological parameters, on DNA damage and on brain and liver histology in the rat. Rats received either saline or Cannabis sativa at 5, 10 or 20 mg/kg (expressed as ?9-tetrahydrocannabinol), intraperitoneally daily for 30 days. Cholesterol, triglycerides, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), total proteins, glucose were determined in serum. DNA fragmentation was measured in the liver. The level of DNA damage of peripheral blood mononuclear cells (PBMCs) was evaluated by alkaline single cell gel electrophoresis (comet assay). Brain and liver histopathology and caspase-3 immunohistochemistry were performed. Cannabis treatment resulted in increased cholesterol (41.2% by 20 mg/kg cannabis) and triglycerides (17.8-31.8% by 10-20 mg/kg cannabis). HDL-C decreased by 21.9-38.4% while LDL-C increased by 14.7-174.7% by 10-20 mg/kg cannabis. Total proteins were unaltered but glucose increased by 34.2-53.3% by 10-20 mg/kg of cannabis. CD4 increased by 16.6-19.5% by 10-20 mg/kg cannabis. Liver DNA fragmentation increased by 16.7% after cannabis at 20 mg/kg. The comet percentage of PBMCs was higher after 5, 10 and 20 mg/kg cannabis (7.0 ± 0.36, 9.0 ± 0.92 and 21.0 ± 0.97) than that in saline control group (5 ± 0.36). Cannabis caused dark neurons, decreased size of nuclei, cellular infiltration and increased caspase-3 immunoreactivity. In the liver, cannabis treatment was associated with fibrosis, vacuolar degeneration, cellular infiltration in the portal area, dilatation of portal vein and positive reaction to caspase-3 antibody. These effects of cannabis were dose-dependent.

Assessment of Potential Mutagenic Effect of Colorant of Some Commercial Fruit Drinks in Mice

Due to the large consumption of commercial fruit drinks worldwide in recent years and considering that some of the components present in their composition cause potential risks to human health, therefore, this study was designed to evaluate the potential mutagenic effect of colorants of commercial fruit drinks (pear, cherry, strawberries and red grape) stored at 4°C for six months, on mice using comet assay, DNA fragmentation , and micronucleus test as a good indicators for strand breaks in DNA, as well measuring the malondialdehyde (MDA) level. Three doses 0.8, 1.6 and 2.4 mg/kg bw of 4 commercial fruit drinks were administered orally for mice for 3 weeks beside the control group. Mice were sacrificed 24 hours after the last dose and subjected to micronucleus and comet assays as well DNA degradation and MDA analysis. The results revealed that a significant increase in tail length of comet percentages from blood cells as well in the frequency of micronucleated cells (MNCs) and DNA fragmentation following administration of commercial fruit drinks was achieved compared to control group. The level of MDA was increased (P<0.05) significantly after administration of commercial fruit drinks especially with the high dose (2.4 mg/ kg bw) of treatment compared to control. In conclusion, this study serves as a warning about the consumption of commercial fruit drinks and for the need for further studies in order to evaluate the long term mutagenic effect of these colorants on human health since some soft drinks are consumed daily by a significant proportion of the world population.

Oxidative dna Damage of Lymphocytes in Peripheral Blood and Ascites in Cancer Patients

Patients with malignant ascites (ma) usually experience poor quality of life, and treatment of this symptom remains a challenge. Oxidative stress, which can cause oxidative damage to dna, plays a pivotal role in carcinogenesis; however, the relationship between oxidative stress and dna damage to tumour-associated lymphocytes (tals) in ma is unclear. We measured the total antioxidant capacity (tac) of plasma and ma supernatant in 31 cancer patients with ma, and we used a comet assay to assess dna damage to both peripheral blood mononuclear cells (pbmcs) and tals. Measurements in age- and sex-matched healthy volunteers were used as controls. The tac of plasma was remarkably lower in cancer patients (9.73 ± 1.96 U/mL) than in healthy control subjects (11.31 ± 1.50 U/mL, p < 0.001). The tac of ma supernatant (6.34 ± 1.57 U/mL) was significantly lower than that of plasma in cancer patients (7.42 ± 1.36 U/mL, p < 0.001). The comet percentage of pbmcs was higher in cancer patients (17.26% ± 6.04%) than in healthy control subjects (9.44% ± 4.47%, p < 0.01). In cancer patients, the comet percentage of tals (36.14% ± 17.85%) was significantly higher than that of pbmcs (17.26% ± 6.04%, p < 0.001). In cancer patients with ma, negative correlations were observed between plasma tac and dna damage to pbmcs (r = -0.505, p = 0.004) and between the tac of ma supernatant and the comet percentage of tals (r = -0.588, p = 0.001). Results indicate the presence of significant oxidative damage to the dna of lymphocytes in peripheral blood and ascites from patients with ma, being especially higher in the cells from ascites. The lower tac of ma supernatant may be related to a higher degree of dna damage to tals. The present study suggests that an oxidant-antioxidant imbalance may be one of the mechanisms leading to the dna damage detected in peripheral blood and local tals in patients with ma, which may provide a novel approach to the treatment of ma.

Helicobacter Pylori –Infected Patients

Background: The role of Helicobacter pylori on gastric carcinogenesis is still unclear but it is considered to predispose carriers to gastric cancer.Objective: The aim of this study is to investigate the relationship between the extent of DNA damage of normal gastric epithelial cells and H. Pylori positive &amp; negative gastritis according to the histological diagnosis.Methods: We compared the percentage of cometed cells on the surface of gastric epithelial cells to the cells beneath gastric mucosal cells by the process of serial incubations times. DNA damage was evaluated by the alkaline single cell gel electrophoresis (comet assay) for 52 cases ,compared 19 normal individuals with 19 patients of H.Pylori positive &amp; negative gastritis and further 14 mixed cases with different histology grading were tested by comet procedure for detection of the relationship of histological diagnosis with DNA damage (comet percentage).Results: There was a relationship between the comet percentage and the histological diagnosis. Comet percentages in specimens from case with normal histology were significantly higher than comet percentages in specimen from case with H. pylori positive gastritis.Conclusion: There was a significant increase in the percentage of cometed cells on the surface of gastric epithelial cells in both normal and infected H. pylori cells compared to the same specimen in the subsequent gastric cell layers.

Relationship between the Extent of DNA Damage and Gastritis in Normal and Helicobacter pylori-Infected Patients

Background/AimsThe role of Helicobacter pylori in gastric carcinogenesis is unclear, but H. pylori infection is thought to predispose carriers to gastric cancer. The aim of this study was to investigate the relationship between the extent of DNA damage in normal gastric epithelial cells and H. pylori-positive and -negative gastritis according to histological diagnosis. We also compared the percentage of cometed cells on the surface of the gastric epithelial cells to the percentage beneath the gastric mucosal cells using serial incubations times.MethodsThe comet assay is a rapid, efficient and reproducible measure of DNA damage in single cell and it was used in this study. DNA damage was evaluated in 52 cases using alkaline single cell gel electrophoresis (comet assay). Comparisons were made between 19 normal individuals, 19 patients with H. pylori-positive and -negative gastritis and 14 mixed cases with different histology gradings to determine if there was a relationship between histological diagnosis and DNA damage (comet percentage).ResultsThe comet percentages in specimens from cases with normal histology were significantly higher than the comet percentages in specimens from cases with H. pylori-positive gastritis. In addition, there was a significant increase in the percentage of cometed cells on the surface of gastric epithelial cells in both normal and H. pylori-infected cells compared to the subsequent gastric cell layers of the same specimen.ConclusionsA relationship between the comet percentage and the histological diagnosis was observed.

Abstract 4209: Genotoxic effects of arsenic trioxide-induced oxidative stress in human hepatocellular carcinoma (HepG2) cells

Abstract Recent studies in our laboratory indicated that oxidative stress plays a key role in arsenic trioxide (ATO)-induced cytotoxicity in human cancer cells. In the present investigation, we used human hepatocellular carcinoma (HepG2) cells as a model to determine whether arsenic induced DNA damage is mediated through oxidative stress. To achieve this goal, oxidative stress biomarkers were measured by lipid peroxidation, glutathione peroxidase, and catalase assays, respectively. The degree of DNA damage was estimated by the means of comet assay. The results of the lipid peroxidation showed a significant increase (p &amp;lt;0.05) of malondialdehyde (MDA) levels with increasing ATO concentrations. Results from the glutathione peroxidase and catalase assays showed a gradual decrease in antioxidant enzyme activity in ATO-treated cells as compared the control. In regard to the comet assay, a significant increase (p &amp;lt; 0.05) in comet tail-length and percentages of DNA cleavage were observed in ATO-treated cells using the comet assay. Taken together, our research demonstrated that oxidative stress modulates ATO mediated DNA damage in HepG2 cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4209. doi:10.1158/1538-7445.AM2011-4209

Where do long-period comets come from? 26 comets from the non-gravitational Oort spike

The apparent source region (or regions) of long-period comets as well as the definition of the dynamically new comet are still open questions.The aim of this investigation is to look for the apparent source of selected long period comets and to refine the definition of dynamically new comets. We show that incorporation of the non-gravitational forces into the orbit determination process significantly changes the situation. We determined precise non-gravitational orbits of all investigated comets and next followed numerically their past and future motion during one orbital period. Applying ingenious Sitarski's method of creating swarms of virtual comets compatible with observations, we were able to derive the uncertainties of original and future orbital elements, as well as the uncertainties of the previous and next perihelion distances. We concluded that the past and future evolution of cometary orbits under the Galactic tide perturbations is the only way to find which comets are really dynamically new. We also have shown that a significant percentage of long-period comets can visit the zone of visibility during at least two or three consecutive perihelion passages.

DNA damage and cell death assessment in patients with severe multiple trauma using comet assay

Purpose: To determine the DNA strand breaks, oxidative DNA damage and cell death in blood and plasma total antioxidant status (TAOS) in 22 patients with severe multiple trauma. Materials and methods: The DNA comet assay was used to measure DNA strand breakage, 8-oxoguanine levels and apoptotic and necrotic nuclei in after admission (day 0) and on days 3, 5, 7 and 15. TAOS was determined by colorimetric method. Results: Trauma patients had high DNA damage at admission (p < 0.01), that further increased with maximum value on day 5 (p < 0.001). On day 15 the degree of DNA damage remained significantly elevated (p < 0.01). No significant difference in the 8-oxoguanine levels at all days examined was found. Patients had a high percentage of apoptotic and necrotic comets at admission, with maximum values on days 3 and 5. A significantly lower TAOS was observed in patients on admission and days 3, 5, 7 and 15 (p < 0.001 in all cases). A decreasing of TAOS on days 7 and 15 compared to that on admission (p < 0.05) was observed. Conclusions: Blood cells from severe trauma patients’ display increased DNA damage associated with apoptosis and necrosis. Reduced plasma TAOS and a tendency to increase of 8-oxoguanine in DNA was observed.

Evaluation of a suitable DNA damage biomarker for human biomonitoring of exposed workers

The objective of this study was to identify a sensitive and noninvasive biomarker of early genotoxic effects, for health risk assessment of workers exposed to mixtures of low doses of xenobiotics. We studied 30 workers exposed to antineoplastic drugs, 57 workers exposed to different mixtures of polycyclic aromatic hydrocarbons (PAHs) (41 airport workers and 16 paving workers) and 76 controls. Comet and micronucleus (MN) tests were performed on lymphocytes and exfoliated buccal cells. The MN assay on lymphocytes did not show significant differences between exposed and controls, while the MN assay on exfoliated buccal cells showed higher values in workers exposed to antineoplastics as compared with controls (0.85 vs. 0.48, P = 0.042). The comet assay on lymphocytes showed a higher comet percentage value (18.11 vs. 11.24 in controls, P = 0.001) and mean tail moment (TM) value (21.84 vs. 16.72 in controls, P = 0.003) in individuals exposed to PAHs as compared with controls; no significant differences were found in exposed to antineoplastics. The comet assay on exfoliated buccal cells did not show significant differences between exposed and control groups for comet percentages, whereas the TM value was higher in workers exposed to PAHs (55.1 vs. 32.31 for controls, P < 0.001). These results show that exfoliated buccal cells, obtained by a noninvasive procedure, represent robust target cells to assess the occupational exposure to inhalable mixture of chemicals at low doses. The comet assay seems to be suitable to promptly evaluate the genotoxic effects of PAHs mixtures that also contain volatile substances. The MN test is suitable to evaluate the effects of antineoplastics. Inc.

Evaluation of Direct-Oxidative DNA Damage on Human Lung Epithelial Cells Exposed to Urban Airborne Particulate Matter

Airborne particulate matter (PM) extracts were investigated for their content of organic compounds and for the direct and oxidative DNA damage induced on lung epithelial cells A549. PM10 was seasonally collected at two monitoring sites (Stations 1 and 2), characterized by different traffic loads. The cells were exposed for 30 min to extracts of PM10 diluted at 0.025%, 0.05%, and 0.1% for summer samples, and at 0.05%, 0.1%, and 0.15% for winter samples. Oxidative and direct DNA damage were evaluated by formamidopyrimidine glycosylase (fpg) comet assay analyzing tail moment (TM) values from fpg-enzyme-treated cells (TMenz) and enzyme untreated cells (TM) respectively and by comet percentage analysis. Measurements relating to Station 2 showed higher levels of polycyclic aromatic hydrocarbons (PAHs), and their methyl-(methyl-PAHs) and nitro-(nitro-PAHs) derivatives in both the seasons. Nitro-PAH concentrations were higher in summer than in winter at both the stations. We found a significant increase of comet percentages at the highest dose of extract from both stations in summer and from Station 2 in winter. The TM and TMenz values relative to the summer sampling showed an early oxidative DNA damage induction also followed by direct DNA damage more evident at Station 2, that seems to correlate with the presence of higher nitro-PAH concentrations during the warm season. At both monitoring stations, the results from winter sampling campaign showed a direct DNA damage induction at 0.1% of extract and oxidative-direct DNA damage at the highest dose (0.15%).

Genotoxicity evaluation of low doses of clodinafop-propargyl to the silkworm Bombyx mori using alkaline single-cell gel electrophoresis

In the present study, DNA damage caused by clodinafop-propargyl was evaluated in silkworm, Bombyx mori, by the alkaline single-cell gel electrophoresis (SCGE). The second, fourth and fifth instar larvae of silkworm were exposed to clodinafop-propargyl by oral feeding with mulberry leaves treated using the different concentration of 30, 60, 120, 240, 480 mg L −1, respectively. The results showed that comet percentage, the head DNA percentage, tail DNA percentage, tail length, tail moment and olive moment of the five tested groups were significantly different from the controlled group ( P < 0.01). A statistically significant (olive tail moment, P < 0.01) dose-dependent increase in DNA damage was observed in silkworm. In addition, the significant dose-dependent reduce in percentage of cocooning and pupating was found in the second instar larvae of silkworm exposed to clodinafop-propargyl. To our knowledge, this was the first report describing the genotoxicity assessment of pesticide using silkworm by the alkaline SCGE.

Sister Chromatid Exchange and Oxidative DNA Damage in Paving Workers exposed to PAHs

Paving workers are exposed during road paving to several polycyclic aromatic hydrocarbons (PAHs) contained in asphalt fumes. In this study early genotoxic and oxidative effects of exposure to bitumen fumes were evaluated in 19 paving workers and 22 controls. Environmental and biological monitoring of exposure was carried out, measuring, on personal air samples from exposed workers collected during three working days, the concentration of 14 PAHs and urinary OH-pyrene at the end of each of the three working days. Genotoxic effect was evaluated analysing sister chromatid exchange (SCE) frequency and direct-oxidative DNA damage by formamido-pyrimidine-glycosylase (Fpg)-modified comet assay on lymphocytes. Tail moment values from Fpg-enzyme treated cells (TMenz) and from untreated cells (TM) were used as parameters of direct and oxidative DNA damage, respectively. For each subject, the TMenz/TM ratio >2.0 was used to indicate the presence of oxidative damage. DNA damage was also evaluated analysing comet percentage. Personal air samples showed low level of total PAHs (2.843 microg m(-3)) with prevalence of 2-3 ring PAHs (2.693 microg m(-3)). Urinary OH-pyrene after work-shift of the three working days was significantly higher than that found at the beginning of the working week. SCE analysis did not show any difference between two groups while an oxidative DNA damage was found in 37% of exposed with respect to the absence in controls. Comet percentage was significantly higher (P = 0.000 ANOVA) in the exposed than in controls. The results demonstrate the high sensitivity of comet assay to assess early oxidative effects induced by exposure to bitumen fumes at low doses and confirm the suitability of urinary OH-pyrene as a biomarker of PAH exposure. In conclusion the study suggests the use of Fpg-modified comet test as a biomarker of early genotoxic effects and that of urinary OH-pyrene as a biomarker of PAH exposure to furnish indications in terms of characterization, prevention and management of risk in occupational exposure to mixtures of potentially carcinogenic substances.

DNA damage in peripheral lymphocytes of untreated breast cancer patients

Using the alkaline comet assay, DNA single-strand breaks (ssb) have been described in peripheral blood lymphocytes (PBL) from breast cancer patients without treatment, but there is no information concerning the occurrence of double-strand breaks (dsb) in the same patients. The purpose of this study was to investigate whether PBL of untreated sporadic breast cancer patients harbor an elevated number of both DNA strand breaks. Forty breast cancer patients without family history of cancer in clinical stage III devoid of treatment and 60 age-matched healthy subjects without history of breast cancer were included. PBL from freshly drawn blood were processed following two different methods: the alkaline and the neutral comet assay. Percentage and tail moment were assessed under fluorescence microscopy and a computer-based image analysis system. In controls, ssb were found in 18 +/- 4.67% of PBL, and dsb at 7.99 +/- 3.67% of PBLs. Cancer patients had higher values of both ssb 24.08 +/- 4.96 (p <0.05) and dsb 13.11 +/- 3.2% (p <0.01). Tail moment for ssb was 6.23 +/- 1.44 and dsb, 2.31 +/- 1.09 for controls. For breast cancer patients, tail moment for ssb was 11.73 +/- 2.40 and for dsb, 6.33 +/- 1.75 (p <0.01). On plotting individual measurements of comet percentage against tail moment for alkaline and neutral comet assays, clear separation of control group from cancer patients can be seen in both assays. Demonstration of two types of DNA damage in PBL of breast cancer patients devoid of treatment or without exposure to environmental genotoxic agents provides a better picture of the degree of DNA damage present in somatic cells of these patients.

A 2.5-Year Genotoxicity Profile for a Partially Restored Polluted River

This study evaluates water genotoxicity of the Kishon River, the most polluted river in Israel that is under restoration. Water samples were collected every other month (January 2001-May 2003) from five sites, and genotoxicity was assayed by the alkaline comet assay using a fish hepatoma cell line (RTH-149). Genotoxicity in the Kishon River was reduced during 2002 as compared to the previous year. The results further revealed fluctuations in genotoxicity levels at all sites throughout the studied period with variations for the same month during consecutive years and seasonality. In general, summer samples were more genotoxic than winter samples. In the vast majority of the 75 water samples, all four parameters for genotoxicity that were employed revealed significant higher genotoxic levels than the controls. Comet percentage values in Kishon River samples were, on average, 1.8-2.4 times higher than controls. Damage score, comet tail length, and cumulative tail length values were 2.2-3.1, 2.4-3.7, and 2.4-3.7 times higher than controls, respectively. The Histadrut Bridge and Haifa fishing harbor (3.0 m depth) emerged as the most polluted sites, whereas Kiryat Haroshet was the least contaminated. Results call for a long-term genotoxicity follow-up plan at the Kishon River in order to assess the possibly evolving chronic genotoxicity state.