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Introduction: Cells other than lymphocytes may be preferable as surrogate biomarkers during exposure monitoring. In nutritional toxicology, cells from colorectal tissues are particularly relevant for studying associations between food and cancer. Thus, we have previously shown that colonic cells of males have higher levels of DNA damage than females, which (among other factors) could be due to a higher consumption of alcoholic beverages by males. To test this hypothesis, we have performed a first exploratory study to compare DNA damage in rectal cells from biopsies of male patients with alcohol abuse and of male and female controls. Peripheral blood lymphocytes were additionally monitored to assess systemic exposure loads., Methods: Cells were isolated and subjected to microgelelectrophoresis +/- endonuclease III to measure DNA breaks and oxidized pyrimidine bases ("comet-assay"). Cell aliquots were treated with H(2)O(2) for 5min in suspension culture and processed immediately or after 60min to determine induced damage and its persistence., Results: Pooled data from subjects of all groups revealed that oxidative DNA damage in rectal cells directly correlated to damage in lymphocytes. Female controls had lower levels of DNA damage than male controls, confirming the previous studies. An unexpected result was that male alcohol abusers had significantly less genetic damage than male controls. Also, repair was detected in lymphocytes of male alcohol abusers and female controls, but not in male controls., Conclusion: This is the first time the comet-assay has been used to detect genotoxicity in human rectal cells as a biomonitoring tool. Our pilot study confirms earlier reports on sex differences and indicates a good correlation between damage in rectal cells and damage in lymphocytes and implies that alcohol exposure enhances endogenous defence.

To assess genotoxic burdens from chemicals, it is necessary to relate observations in experimental animals to humans. The success of this extrapolation would be increased by including data on chemical activities in human tissues. Therefore, we have developed techniques to assess DNA damage in human gastric and nasal mucosa (GM, NM) cells. Biopsy samples were obtained during gastroscopy from macroscopically healthy tissue of the stomach or from healthy nasal epithelia during surgery. The specimens were incubated for 30-45 min at 37 degrees C with a digestive solution. We obtained 1.5-8 x 10(6) GM cells and 5-10 x 10(5) NM cells per donor, both with viabilities of 80-95%. The cells were incubated in vitro for 1 hr at 37 degrees C with the test compounds added in their appropriate solvents. In GM cells, we studied N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), sodium dichromate (Na2Cr2O7), nickel sulphate (NiSO4), cadmium sulphate (CdSO4), and lindane. In NM cells, lindane was investigated. Each compound was assessed for DNA damaging activity in cells of at least three different human donor samples using the microgel single cell assay. Similar studies were performed with GM and NM cells obtained from Sprague-Dawley rats. We have found human GM cells to be more sensitive to the genotoxic activity of MNNG than rat GM cells (low effective concentration [LEC] = 0.16 and 0.625 micrograms/ml for human and rat, respectively). Human cells were also more sensitive to the cytotoxic/genotoxic activity of NiSO4 (LEC = 5 and 19 mumoles/ml for human and rat, respectively). CdSO4 was genotoxic in human GM cells (LEC = 0.03-0.125 mumoles/ml), whereas no dose-related genotoxicity was observed in rat GM at concentrations up to 0.5 mumoles/ml. In contrast, approximately equal responses regarding genotoxicity and cytotoxicity were observed in rat and human GM for Na2Cr2O7 (0.25-1 mumoles/ml). Lindane, however, was genotoxic in three out of four rat GM but not in human GM cells (0.5-1 mumoles/ml), whereas it was active in both rat and human NM cells. Together with other recently published in vivo findings, our results with lindane can be interpreted according to a parallelogram approach. In view of possible human exposure situations and the sensitivities of the two target tissues from both species, the data imply that lindane will pose a health risk to humans by inhalation but not by ingestion.

In view of the high incidence of dietary-related tumors, one important research goal is to identify the participating genotoxic carcinogens and the nutritional factors that may counteract their activities. We therefore have further developed a method to assess DNA damage in tumor target tissues of the gastrointestinal tract. Subsequently the prevention of this inducible DNA damage by lactic acid bacteria and by milk products fermented with probiotics was studied as well. The microgel electrophoresis technique was applied to cells of the esophageal, gastric, duodenal, and colonic mucosa. Cells were grouped according to their degree of DNA damage, the simplest measure of which is to discriminate between those with damage (comets) and those without damage. When these cells were isolated from animals treated with a genotoxic carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and exposed to MNNG for 1-24 hours, it was possible to follow the course of genotoxicity throughout the gastrointestinal tract. After the animals were treated with the lactic acid bacteria under study, it was possible to detect antigenotoxic properties as well. The gavage of 10(10) viable Lactobacillus casei cells in 10 ml of 0.9% NaCl per kilogram body weight immediately before the oral administration of MNNG (5 mg/kg body wt) resulted in a reduction of induced DNA damage in gastric and colonic mucosa cells. A sequential treatment schedule was even more effective: when the animals were treated orally with lactic acid bacteria or yogurt (10 ml/kg body wt) in the morning followed by MNNG (7.5 mg/kg body wt) eight hours later and the colon cells were isolated 16 hours later, the percentages of cells remaining intact were distinctly higher in the combination groups (68 +/- 10 and 68 +/- 19 for L. casei and a "Bio" yogurt, respectively) than in the group receiving only MNNG (45 +/- 17). The effect of heating L. casei was studied and was found to yield less clear-cut effects in preventing genotoxicity. The method is an efficient tool to elucidate antigenotoxic properties of food components in vivo in those target tissues actually afflicted by dietary-related tumors.