Eating habits trajectories of students using university canteens

Background

Diets among the young often do not meet recommendations thus increasing the risk of developing chronic condition in adulthood. The present study aims at evaluate dynamics of eating habits among university students using data automatically recorded by cashier transactions at canteen.

Methods

The study population consisted of 8,338 students enrolled in bachelor courses at Pisa University in 2010-2014 and accessing canteens at least once all over their courses duration (three year). Analyses were performed merging the administrative archive of the University of Pisa and the database of cashier transactions at university canteens. The frequency of different food-groups choice over years was evaluated using a zero- and one-inflated beta regression models, while latent class analysis (LCA) and posterior probabilities derived from that were used to evaluate the evolution of eating habits.

Results

In adjusted models, the proportion of fruit choices increased significantly in both the second (β = 0.077[0.013]) and third year of registration (β = 0.233[0.018]), similarly for vegetables (β = 0.090[0.011] and β = 0.065[0.015]). Conversely, the selection of foods commonly labelled as unhealthy decreased over registration years. LCA revealed 4 different classes each year. The 4 classes distinguished “healthy eaters” (LC1), those often choosing sweets, potatoes and legumes (LC2 “lazy eaters”), “greedy and quick eaters” (LC3) favoring the selection of fried foods, sandwiches and sweets while LC4 represented “selective eaters” composing their meals combining mainly grains and vegetables. The probability of being a “lazy” or “greedy and quick” eaters declined significantly overs registration years. “Selective eaters” almost doubled over years while the probability of belonging to the “healthy” class showed a weak increase over years.

Conclusions

During the years following enrollment students tended to limit choices towards unhealthy foods in favors of healthier dishes.

Key messages

Intervention for the promotion of healthy eating among young adults is essential as awareness of choices may raised only in adulthood. The present work outline the use of digital traces for public health research.

Taste receptor polymorphisms and male infertility

STUDY QUESTION

Are polymorphisms of taste receptor genes associated with male infertility?

SUMMARY ANSWER

This study has showed the associations between three single nucleotide polymorphisms (SNPs) in taste receptors genes (TASR) and male infertility.

WHAT IS KNOWN ALREADY

Recent studies showed the expression of taste receptors in the testis and in spermatozoa, suggesting their possible role in infertility. The vast genetic variability in taste genes results in a large degree of diversity in various human phenotypes.

STUDY DESIGN, SIZE, DURATION

In this study, we genotyped 19 SNPs in 12 taste related genes in a total of 494 Caucasian male patients undergoing semen evaluation at the Centre of Couple Sterility of the Siena University Hospital. Consecutive patients were enrolled during infertility investigations from October 2014 to February 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Median age of the patients was 36 years (18-58) and 141 were smokers. Genotyping was performed using the allele-specific PCR. The statistical analysis was carried out using generalized linear model (GLM) to explore the association between age, smoking, the genetic polymorphisms and sperm parameters.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed that the homozygous carriers of the (G) allele of the TAS2R14-rs3741843 polymorphism showed a decreased sperm progressive motility compared to heterozygotes and (A) homozygotes (P = 0.003). Moreover, the homozygous carriers of the (T) allele of the TAS2R3-rs11763979 SNP showed fewer normal acrosome compared with the heterozygous and the homozygous carriers of the (G) allele (P = 0.002). Multiple comparisons correction was applied and the Bonferroni-corrected critical P-value was = 0.003.

LIMITATIONS, REASONS FOR CAUTION

The analysis is restricted to SNPs within genes and to men of Caucasian ancestry.

WIDER IMPLICATIONS OF THE FINDINGS

In silico analyses strongly point towards a functional effect of the two SNPs: TAS2R14-rs3741843 regulates TAS2R43 expression, a gene that is involved in cilia motility and therefore could influences sperm mobility; the (T) allele of TAS2R3-rs11763979 increases the expression of the WEE2 antisense RNA one gene (WEE2-AS1). According to Genotype-Tissue Expression (GTEx) project the WEE2 gene is expressed in the testes where presumably it has the role of down regulating meiotic cell division. It is plausible to hypothesize that the WEE2-AS1 increased expression may down regulate WEE2 which in turn can alter the natural timing of sperm maturation increasing the number of abnormal sperm cells.

STUDY FUNDING/COMPETING INTEREST(S)

None.

Multidimensional Evaluation of Endogenous and Health Factors Affecting Food Preferences, Taste and Smell Perception

OBJECTIVE

This study, by taking a holistic approach, investigates the relationships between taste, smell sensitivity and food preference with prognostic (endogenous and health) factors including age, gender, genetic taste markers, body mass, cigarette smoking, and number of drugs used.

DESIGN

Cross sectional study.

SETTING

Northern Italy.

PARTICIPANTS

203 healthy subjects (160 women/43 men; mean age: 58.2±19.8 years) were examined.

MEASUREMENTS

Individual taste sensitivity was determined by saccharose, sodium chloride, acetic acid and caffeine solutions and by 6-n-propylthiouracil (PROP) responsiveness test. Olfactory sensitivity has been assessed by «Sniffin' Sticks». Four tag Single nucleotide polymorphisms (SNPs) in regions of interest were genotyped. Factor analysis and multivariate regression were performed for scaling food preferences and screening prognostic factors, respectively.

RESULTS

Increasing age is associated with decreased responsiveness to NaCl (P=0.001), sweet solutions (P=0.044), and smell perception (P<0.001). Concerning the food preferences, elderly like the "vegetables" and "fruits" but dislike "spicy" more than younger. Regarding number of drugs taken, there is a significant negative effect on smell perception (P<0.001). In addition, drugs reduce both the "vegetables foods" score (P=0.002) and the "milk-product foods" score (P=0.027). With respect to Body Mass Index (BMI), only a significant effect was shown, on sweet perception (P=0.006). Variation in taste receptor genes can give rise to differential perception of sweet, acid and bitter tastes. No effect of gender and smoking was observed.

CONCLUSIONS

Our study suggested that age, genetic markers, BMI and drugs use are the factors which affect taste and smell perception and food preferences.

Single nucleotide polymorphism detection by optical DNA-based sensing coupled with whole genomic amplification

The work presented here deals with the optimization of a strategy for detection of single nucleotide polymorphisms based on surface plasmon resonance imaging. First, a sandwich-like assay was designed, and oligonucleotide sequences were computationally selected in order to study optimized conditions for the detection of the rs1045642 single nucleotide polymorphism in the gene ABCB1. Then the strategy was optimized on a surface plasmon resonance imaging biosensor using synthetic DNA sequences in order to evaluate the best conditions for the detection of a single mismatching base. Finally, the assay was tested on DNA extracted from human blood which was subsequently amplified using a whole genome amplification kit. The direct detection of the polymorphism was successfully achieved. The biochip was highly regenerable and reusable for up to 20 measurements. Furthermore, coupling these promising results with the multiarray assay, we can foresee applying this biosensor in clinical research extended to concurrent analysis of different polymorphisms.

Genetic polymorphisms associated with outcome in multiple myeloma patients receiving high-dose melphalan

High-dose melphalan (HDM) is an essential component in the treatment of patients with multiple myeloma (MM). Few data are available regarding genetic polymorphisms associated with patient outcome or toxicity in this setting. To identify such polymorphisms, we performed a retrospective analysis, genotyping single nucleotide polymorphisms (SNPs) with the arrayed primer extension (APEX) technology in 169 patients having received HDM for MM. We analyzed 209 SNPs in 95 genes involved in drug metabolism, DNA repair, cell cycle and apoptosis. SNPs in ABCB1, CYP3A4 and TP53BP2 were associated with response to VAD induction therapy (P<0.01). SNPs in ALDH2, GSTT2 and BRCA1 were associated with response to HDM (P<0.01). Polymorphisms in CYP1A1, RAD51 and PARP were associated with disease progression whereas polymorphisms in ALDH2 and CYP1A1 were correlated with OS. Polymorphisms in BRCA1, CDKN1A and XRCC1 were associated with the occurrence of severe mucositis after HDM. These results suggest that SNPs of genes involved in drug metabolism or DNA repair could be used to distinguish MM patient subgroups with different toxicity/efficacy profiles.

Oxidative and genotoxic damage after radio‐iodine therapy of Graves' hyperthyroidism

PURPOSE

To evaluate genetic damage and oxidative stress following a single therapeutic dose of 131I in Graves' disease patients monitored up to 180 days after treatment.

MATERIALS AND METHODS

Genetic damage induction was estimated as the increase in micronuclei in peripheral lymphocytes of patients. As indicators of radiogenic oxidative stress, vitamin E and lipoperoxide levels were assessed in the plasma of patients, as well as the release of plasmic clastogenic factors measured by the induction of micronuclei in vitro in peripheral lymphocytes of a healthy donor.

RESULTS

Vitamin E depletion lasted at least 3 days and the basal level was restored within 7 days. No statistically significant variations were observed in lipoperoxide plasma levels. A sharp increase of micronuclei in the peripheral lymphocytes of patients was correlated (p < 0.001) with the release of clastogenic factor in the plasma. The highest micronucleus value was negatively correlated (p < 0.03) with the lowest vitamin E level observed in each patient.

CONCLUSIONS

Micronuclei induction was the direct consequence not only of the energy deposition of 131I on the genetic material, but also of oxidative stress, likely via the release of clastogenic factor.

Perturbation of murine liver cyp-superfamily of isoforms by different combinations of pesticide mixtures

It was previously found that fenarimol, vinclozolin or acephate, three of the most used pesticides worldwide, provoked a marked perturbation of murine cytochrome P450 (CYP)-linked monooxygenases. Here, to more closely mimic human exposure, it was investigated whether different pesticide combinations administered i.p. in male Swiss Albino CD1 mice in single or repeated fashion (daily, for three consecutive days), affect CYP-dependent oxidations. The four simulated mixtures showed a complex pattern of CYP induction and suppression, especially after repeated injection. For example, while fenarimol alone was the most inducing agent--reaching a 79-fold increase over control in testosterone 2alpha-hydroxylase--followed by vinclozolin and acephate, coadministration with the former markedly reduced induction. Coadministration with vinclozolin, determined various positive and negative modulations. An increase of CYP2B1/2 and CYP3A1/2-associated oxidases and a decrease of ethoxycoumarin metabolism was observed in the acephate and vinclozolin mixture. An equivalent or reduced CYP expression, if compared to double combinations, was seen using the complete mixture. Taken as a whole, the unpredictability of the recorded effects with simple mixtures, shrinks the misleading extrapolation performed on a single pesticide. If reproduced in human, such changes, altering either endogenous metabolism or biotransformation of ubiquitous toxins, might have public health implications.

Anticlastogenic effect of Ginkgo biloba extract in Graves' disease patients receiving radioiodine therapy

BACKGROUND

Chromosomal damage, as assessed by clastogenic factors (CFs) and micronuclei (MN) appearance, after radioiodine therapy of Graves' disease has been reported.

OBJECTIVE AND METHODS

Our objective was to evaluate the effect of Ginkgo biloba extract (EGb 761) supplementation on the time course (up to 120 d) of CFs and MN appearance in lymphocytes from patients with Graves' disease after iodine-131 ((131)I) therapy. Patients were randomly assigned to EGb 761 or placebo, in a blinded manner.

RESULTS

In the placebo group, MN increased early (P < 0.001) after (131)I, peaking at the 21st day (P = 0.0003) and declining thereafter. In EGb 761-treated patients, MN increased early (P < 0.05), while returning toward baseline value thereafter. Therefore, mean MN increment was significantly higher in the placebo group as compared with EGb 761-treated patients (P < 0.01). Moreover, an early (P < 0.0001) and sustained (up to 35 d; P < 0.001) MN increase induced by CFs was observed in the placebo group. Conversely, in EGb 761-treated patients, MN increase induced by CFs never reached the statistical significance; therefore, the mean of the MN increments was significantly lower than in placebo (P < 0.05). A significant positive correlation between MN maximum increment and the bone marrow dose was observed in the placebo group only (P = 0.03). No significant difference was observed in clinical outcome between the two groups.

CONCLUSIONS

EGb 761 supplementation neutralized genotoxic damage induced by radioiodine treatment, without affecting the clinical outcome. Although (131)I therapy is generally safe, our data suggest that Gingko biloba extracts may prevent genetic effects of radioiodine therapy for hyperthyroid Graves' disease.

DNA repair genetic polymorphisms and risk of colorectal cancer in the Czech Republic

Colorectal cancer represents a complex disease where susceptibility may be influenced by genetic polymorphisms in the DNA repair system. In the present study we investigated the role of nine single nucleotide polymorphisms in eight DNA repair genes on the risk of colorectal cancer in a hospital-based case-control population (532 cases and 532 sex- and age-matched controls). Data analysis showed that the variant allele homozygotes for the Asn148Glu polymorphism in the APE1 gene were at a statistically non-significant increased risk of colorectal cancer. The risk was more pronounced for colon cancer (odds ratio, OR: 1.50; 95% confidence interval, CI: 1.01-2.22; p=0.05). The data stratification showed increased risk of colorectal cancer in the age group 64-86 years in both individuals heterozygous (OR: 1.79; 95% CI: 1.04-3.07; p=0.04) and homozygous (OR: 2.57; 95% CI: 1.30-5.06; p=0.007) for the variant allele of the APE1 Asn148Glu polymorphism. Smokers homozygous for the variant allele of the hOGG1 Ser326Cys polymorphism showed increased risk of colorectal cancer (OR: 4.17; 95% CI: 1.17-15.54; p=0.03). The analysis of binary genotype combinations showed increased colorectal cancer risk in individuals simultaneously homozygous for the variant alleles of APE1 Asn148Glu and hOGG1 Ser326Cys (OR: 6.37; 95% CI: 1.40-29.02; p=0.02). Considering the subtle effect of the DNA repair polymorphisms on the risk of colorectal cancer, exploration of gene-gene and gene-environmental interactions with a large sample size with sufficient statistical power are recommended.

Association of ABCB1/MDR1 and OPRM1 Gene Polymorphisms With Morphine Pain Relief

The pharmacokinetics and pharmacodynamics of morphine are under the control of several polymorphic genes, which can account for part of the observed interindividual variation in pain relief. We focused on two such genes: ABCB1/MDR1, a major determinant of morphine bioavailability, and OPRM1, which encodes for the mu-opioid receptor, the primary site of action for morphine. One hundred and forty-five patients of Italian origin undergoing morphine therapy were genotyped for the single-nucleotide polymorphism (SNP) C3435T of ABCB1/MDR1 and for the A80G SNP of OPRM1. Pain relief variability was significantly (P<0.0001) associated with both polymorphisms. Combining the extreme genotypes of both genes, the association between patient polymorphism and pain relief improved (P<0.00001), allowing the detection of three groups: strong responders, responders, and non-responders, with sensitivity close to 100% and specificity more than 70%. This study provides a good example of the possible clinical use of pharmacogenetics.

Phenotype-genotype relationships of SULT1A1 in human liver and variations in the IC50 of the SULT1A1 inhibitor quercetin

Human sulfotransferases catalyze sulfate conjugation and 2 polymorphic genes, SULT1A1 and SULT1A2 in this family of transferases have been identified, encoding for 2 isoenzymes with very similar properties and substrate specificities. In order to test the hypothesis that variability in sulfation is due to genetic polymorphism in SULT1A1, the sulfation rate of 4-nitrophenol, a diagnostic substrate, was measured in 50 human liver samples and the genotype at the SULT1A1 locus was analyzed. The rate of 4-nitrophenol sulfation varied from 473 - 1,405 pmol/min/mg between the 5th and 95th percentiles, with a median and a mean +/- SD of 757 and 807 +/- 292 pmol/min/mg, respectively. The activities detected among the SULT1A1*2/*2 homozygotes (5 cases) were significantly lower than those of the other 2 genotypes, SULTA1*11/*1 and SULT1A1*1/*2 (5 and 40 cases, respectively), whereas there was no significant difference found between the SULT1A1*1/*1 and SULT1A1*1/*2 genotypes. To evaluate the possible influence of SULT1A2 polymorphism, genotype assays were also performed for this locus. No SULT1A2*2/*2 carrier, 26 SULT1A2*1/*1 and 24 SULT1A2*1/*2 were detected in the population sample under study. However, no correlation between the rate of 4-nitrophenol sulfation and the SULT1A2 genotype was detected. These results confirm that the variation in the rate of 4-nitrophenol sulfation in human liver is mainly due to SULT1A. Since SULT1A1*1/*2 polymorphism accounts for no more than 10% of the phenotypic variation seen in this cohort, other factors must also contribute to the variability in the rate of 4-nitrophenol sulfation in human liver. However, on the basis of the data obtained, variations in age, gender and liver function as possible causative factors can be excluded. The IC50 of quercetin, a potent inhibitor of 4-nitrophenol sulfation, was measured in the liver samples and ranged from 4.6 to 17.3 nM between the 5th and 95th percentiles. The median and the mean +/- SD were 7.7 nM and 8.3 +/- 2.5 nM, respectively. There was a weak but significant correlation between the IC50 value and age of the liver donors (r = 0.283, p = 0.046). The observed variation did not correlate with the genotypes at the SULT1A1 and SULT1A2 loci.

Type 2 diabetes in hepatitis C-related mixed cryoglobulinaemia patients

OBJECTIVES

Mixed cryoglobulinaemia (MC) is a systemic vasculitis frequently associated with hepatitis C virus (HCV) infection. A possible link between HCV infection and type 2 diabetes has been suggested. This study evaluated the prevalence and clinical phenotype of diabetes in MC-HCV+ patients.

METHODS

Two hundred and twenty-nine consecutively recruited MC-HCV+ patients were compared with 217 sex- and age-matched controls without HCV infection.

RESULTS

The prevalence of type 2 diabetes was significantly higher in MC-HCV+ patients than in controls (14.4 vs 6.9%, P < 0.01). Diabetic MC-HCV+ patients were leaner than diabetic patients without MC-HCV (P < 0.0001), and showed significantly lower total and low-density lipoprotein cholesterol levels (P < 0.001) and lower systolic (P = 0.01) and diastolic blood pressure (P = 0.005). MC-HCV+ diabetic patients had non-organ-specific autoantibodies more frequently (34 vs 18%, P = 0.032) than non-diabetic MC-HCV+ patients.

CONCLUSIONS

The prevalence of type 2 diabetes is higher in patients with MC-HCV than in controls. Diabetic MC-HCV+ patients show an attenuated diabetic phenotype and are more likely to carry non-organ-specific autoantibodies.

Oxidative damage and cytogenetic analysis in leukocytes of Parkinson's disease patients

BACKGROUND

Postmortem studies suggest excessive free radical toxicity in the substantia nigra of patients with PD. Increased lipid peroxidation and oxidative DNA damage have been reported in the CNS. Markers of oxidative stress have been identified in the blood of patients with PD.

OBJECTIVE

To assess the presence of spontaneous chromosome and primary or oxidative DNA damage in peripheral blood leukocytes of patients with untreated PD.

METHODS

Patients with de novo PD (20) and control subjects (16), matched for age, sex, and smoking habits, underwent cytogenetic analysis using the human lymphocyte micronucleus assay coupled with the fluorescence in situ hybridization technique and the Comet assay.

RESULTS

Compared with controls, patients with PD showed an increase in the incidence of spontaneous micronuclei (p < 0.001); single strand breaks (p < 0.001); and oxidized purine bases (p < 0.05). Fluorescence in situ hybridization analysis showed micronuclei harboring acentric fragments.

CONCLUSIONS

There is chromosomal, primary DNA damage and oxidative DNA damage demonstrable in lymphocytes of patients with untreated PD.

Lichen (Xanthoria parietina) biomonitoring of trace element contamination and air quality assessment in Pisa Province (Tuscany, Italy)

In the northern part of Pisa Province (Tuscany, Italy), the use of lichens as both airborne trace element biomonitors and air quality bioindicators is described. The following elements were analysed in Xanthoria parietina: As, Cd, Cr, Ni, Pb, V, Zn and Hg, and the results are compared with those we previously obtained in Livorno Province (Tuscany) using the same lichen species. The results identify spots of different environmental metal contamination and air quality. Median values of Pb, V and Ni concentrations were much lower than those of Livorno Province, with maximum values even nine times lower. Arsenic contamination was also lower, while Cd, Hg and Zn levels were similar in the two areas. In Pisa Province, the highest levels of contamination were recorded for Zn, Pb, Cr and Ni, and a degree of agreement was found between air quality and metal concentrations in lichens. The air quality in Pisa Province is better than in Livorno Province, even if the different climatic and orographic features of the two areas may influence the presence of lichen species and thus an assessment of air quality.

Genomic organisation of the mouse Ret proto-oncogene

The RET proto-oncogene is involved in the development of both kidney and neural crests derived tissues. RET deleterious mutations cause hereditary neuroendocrine tumours and congenital intestinal aganglionosis. Ongoing efforts aimed at elucidating the function of this gene include expression studies in different species and in transgenic mice. As first step in the study of Ret expression in mouse, we obtained the mouse Ret genomic structure. Intron-exon boundaries were determined and sequenced, all introns but the first one were amplified and cloned, and exons positioned in a restriction map. Mouse and human genes comparison indicates a highly conserved genomic organisation, except for exon 21 which is not conserved in mouse. A region extending 386 bp 5' to the first exon was sequenced and compared with its human counterpart. Some features, reported for the human promoter, like the absence of TATA or CAAT boxes and a high GC content, are conserved.

Genotype-phenotype correlation for thiopurine S-methyltransferase in healthy Italian subjects

OBJECTIVE

The aim of the present study was to estimate the concordance rate between erythrocyte thiopurine methyltransferase (TPMT) activity and genotype at the TPMT locus in an Italian population sample.

METHODS

The TPMT phenotype and genotype were determined in an unrelated population of 103 Italian healthy blood donors. Erythrocyte TPMT activity was measured with a radiochemical assay using 12.5 microM S-adenosyl-L-(methyl-14C)-methionine and 4 mM 6-mercaptopurine. The genotyping assay was based on restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) and allele-specific oligonucleotide polymerase chain reaction (ASO-PCR) methods.

RESULTS

All subjects had detectable TPMT activity. The activity of TPMT varied 2.8-fold between the 5th and 95th percentile. This variation was neither age (P = 0.63) nor gender (P = 0.44) regulated and the frequency distribution of TPMT activity is compatible with a polymorphic distribution. The presence of the four most common defective alleles, i.e. TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C, was examined through the entire phenotyped population. Ninety-two subjects did not carry any of the tested mutations. Eleven individuals were heterozygous for one of the mutant alleles and had a TPMT activity lower than 30 pmol/min/mg. Eight subjects were TPMT*1/TPMT*3A, two TPMT*1/TPMT*3C and one was TPMT*1/TPMT*2. The TPMT*3B allele was not detected in the samples analysed.

CONCLUSION

There was a concordance of 97% between genotype and phenotype. All the heterozygotes had an intermediate phenotype. However, the wide variation range in TPMT activity detected in the wild-type homozygotes indicates that other genetic or epigenetic factors influence the TPMT phenotype.

Association between canine malignant lymphoma, living in industrial areas, and use of chemicals by dog owners

A case-control study was carried out to determine whether residential exposure to environmental pollutants increased risk for canine lymphoma in pet dogs. One hundred one cases with cytologically or histologically confirmed lymphoma diagnosed at a veterinary teaching hospital between the middle of 1996 and the middle of 1998 were examined. Controls were obtained by choosing twice the number of dogs without neoplastic disease, with overlapping distributions of province of residence, age, sex, and breed. Information regarding animal management, residence type, professional or hobby use of chemicals by owners, and treatment with herbicides or other pesticides in the area frequently visited by the dogs was obtained with a multiple-choice questionnaire by telephone interview. Two variables were positively and independently associated with the disease, namely residency in industrial areas (odds ratio [OR]; = 8.5; 95% confidence interval [CI], 2.3-30.9) and use of chemicals by owners, specifically paints or solvents (OR = 4.6; 95% CI, 1.7-12.6). A significantly lower value of the mean age of disease onset was found in the group of dogs at risk in comparison with the group of all other dogs (6.1 +/- 0.4 years, n = 36 versus 7.5 +/- 0.4 years, n = 65, respectively; P = .008). Variables describing animal care and pesticide use were either not associated with the disease or were uninformative. We suggest that canine lymphoma may be considered a sentinel of potentially hazardous situations for humans, because of the relatively short latency between exposure and disease onset.

DNA damage evaluated by alkaline single cell gel electrophoresis (SCGE) in children of Chernobyl, 10 years after the disaster

Using the alkaline single cell gel electrophoresis (Comet) assay, the extent of DNA damage was evaluated in leukocytes of 43 Belarussian children (16 healthy and 27 affected by thyroid cancer). Thirty-nine healthy children from Pisa (Italy) were enrolled in the study as controls. In addition to basal levels of DNA damage, leukocytes were treated in vitro with bleomycin (BLM), a radiomimetic drug, to evaluate a possible adaptive response in different groups of children. Results with the Comet assay indicated an increased level of DNA damage (P=0.037) in leukocytes of Belarussian children compared to the Italian control group. In addition, within the Belarus group, lower basal levels of DNA damage (P<0.001) were found in children with cancer compared to healthy children. Tumor affected children were living in less radiocontaminated areas (P<0.04) than the healthy children and there was a significant relationship (P=0.03) between the amount of environmental radiocontamination and DNA damage in leukocytes. There were no differences in the sensitivity of leukocytes from different groups of children to BLM, indicating the absence of an adaptive response. The lack of an adaptive response may have been due to the use of noncycling cells and/or the bleomycin dose chosen. Tests for the presence of clastogenic factors (CF) in the blood serum of children showed that 39% of the tumor affected children and 19% of the healthy children in the exposed group were positive as compared to the Italian control group (0%) (Chi-square test, P<0.04). The higher levels of genomic damage in children evaluated 10 years after the Chernobyl disaster could be related to the increased incidence of individuals with CF.

HUman MicroNucleus project: international database comparison for results with the cytokinesis-block micronucleus assay in human lymphocytes: I. Effect of laboratory protocol, scoring criteria, and host factors on the frequency of micronuclei

Micronucleus (MN) expression in peripheral blood lymphocytes is well established as a standard method for monitoring chromosome damage in human populations. The first results of an analysis of pooled data from laboratories using the cytokinesis-block micronucleus (CBMN) assay and participating in the HUMN (HUman MicroNucleus project) international collaborative study are presented. The effects of laboratory protocol, scoring criteria, and host factors on baseline micronucleated binucleate cell (MNC) frequency are evaluated, and a reference range of "normal" values against which future studies may be compared is provided. Primary data from historical records were submitted by 25 laboratories distributed in 16 countries. This resulted in a database of nearly 7000 subjects. Potentially significant differences were present in the methods used by participating laboratories, such as in the type of culture medium, the concentration of cytochalasin-B, the percentage of fetal calf serum, and in the culture method. Differences in criteria for scoring micronuclei were also evident. The overall median MNC frequency in nonexposed (i.e., normal) subjects was 6.5 per thousand and the interquartile range was between 3 and 12 per thousand. An increase in MNC frequency with age was evident in all but two laboratories. The effect of gender, although not so evident in all databases, was also present, with females having a 19% higher level of MNC frequency (95% confidence interval: 14-24%). Statistical analyses were performed using random-effects models for correlated data. Our best model, which included exposure to genotoxic factors, host factors, methods, and scoring criteria, explained 75% of the total variance, with the largest contribution attributable to laboratory methods.

Are baseline frequencies of SCEs, CAs, and MN in human lymphocytes related to hematological values?

In the present study, the correlation among several hematic values and the baseline frequencies of sister chromatid exchanges (SCEs), chromosome aberrations (CAs), and micronucleus (MN) were evaluated in human peripheral blood lymphocytes from a group of 1429 volunteers. Donors were selected to be representative of the general population of people living in the city of Pisa (Italy). By the use of the principal component analysis (PCA), principal components (PCs) were extracted from the complex pattern of correlations intrinsic in the hematic values (for example such as those among hemoglobin content, hematocrit, and erythrocyte count), and were tested for correlation on SCE, CA and MN frequencies. The seven PCs extracted (among 20 hematic values) were either positively or negatively correlated with the three cytogenetic endpoints. However, after correction by independent confounding factors (such as the age), with the use of the coefficient of partial correlation (CPC) analysis, only one PC significantly held the correlation with MN frequencies. This PC had the main contribution from the correlation between the concentration of potassium and the activity of alkaline phosphatase. These variables are known to be markers for bone (calcium) metabolism and are negatively correlated with MN frequencies. Because MN can arise from aneuploidy, the hematic concentrations of calcium may be important for stabilizing the mitotic process in stimulated lymphocytes. Finally, our study shows that the analysis of the hematic values adds very little information and removes a meaningless part of variance of the total variability observed for SCEs, CAs and MN.

Validation of single cell gel assay in human leukocytes with 18 reference compounds

To validate the alkaline single cell gel (SCG) assay as a tool for the detection of DNA damage in human leukocytes, we investigated the in vitro activity of 18 chemicals. Thirteen of these chemicals (pyrene (PY), benzo(a)pyrene (BaP), cyclophosphamide (CP), 4-nitroquinoline-1-oxide (4NQO), bleomycin (BLM), methylmercury chloride (MMC), mitomycin C (MTC), hydrogen peroxide (HP), diepoxybutane (DEB), glutaraldehyde (GA), formaldehyde (FA), griseofulvin (GF), sodium azide (NA)) are genotoxic in at least one cell system, while five compounds (ascorbic acid (AA), glucose (GL), D-mannitol (MAN), O-vanillin (VAN), chlorophyllin (CHL)) are classified as non-genotoxic. In this in vitro SCG assay, PY, BaP and CP were positive with exogeneous metabolic activation (rat S9 mix) while 4NQO, BLM, MMC, MTC, hydrogen peroxide, and diepoxbutane were positive in the absence of metabolic activation. CHL and VAN were unexpectedly found to induce a dose-dependent increase in DNA migration. AA, GL, and MAN were negative in a non-toxic range of doses. GF gave equivocal results, while FA and GA increased DNA migration at low doses and decreased DNA migration at higher doses. This behaviour is consistent with the known DNA damaging and crosslinking properties of these compounds. These data support the sensitivity and specificity of this assay for identifying genotoxic agents.

High prevalence of chromosome 10 rearrangements in human lymphocytes after in vitro X-ray irradiation

PURPOSE

To evaluate the chromosome symmetric or asymmetric rearrangement (CR) frequency for chromosome 10 compared to chromosomes 1 and 3 induced in vitro in human lymphocytes by low doses of X-rays.

MATERIALS AND METHODS

Blood samples obtained from three young and healthy volunteers were irradiated in G0 with 0.25, 0.50 and 1 Gy X-rays. Chromosome painting analysis was used on preparations of peripheral lymphocytes for the identification of CR.

RESULTS

It was found that radiation-induced CR levels were nonrandomly distributed among the three painted chromosomes. Chromosome 10 CR frequencies were significantly greater than those involving chromosomes 1 (at all the doses tested) or 3 (at 0.25 and 1 Gy), with frequency ratios ranging from 2.2 to 5.2.

CONCLUSIONS

In comparison to chromosomes 1 and 3, chromosome 10 appeared to be involved in exchanging at a significantly greater extent than expected according to its DNA content.

Chromosome aberrations in lymphocytes and clastogenic factors in plasma detected in Belarus children 10 years after Chernobyl accident

In 1996, 10 years after Chernobyl accident, a cytogenetic analysis was carried out to assess whether chromosome aberrant cells (CA) were still detectable in the lymphocytes and clastogenic factors (CFs) were present in the plasma of children coming from Gomel (Belarus), one of the most heavily contaminated regions. Furthermore, the possible contribution of plasmatic CFs to the amount of CA was investigated. The presence of CA was examined in the lymphocytes from 29 thyroid tumour-affected children and 41 healthy children (local controls). Thirty healthy children living in Pisa (Italy) were enrolled in the study as additional controls from an uncontaminated area. No significant difference was observed between the two control groups, whereas a significantly increased frequency of CA was found in the tumour-affected children, as compared with Gomel and Pisa controls (chi 2-test, p < 0.001). However, when soil contamination level was taken into account, the chromosome type CA frequency observed in tumour-affected children coming from the more contaminated areas (> 4 Ci/km2) resulted significantly higher than that in other children, either affected or not (p = 0.003). The presence of CFs was analyzed on the plasma ultrafiltrate from 41 children. 7/10 (70%) plasma samples from tumour-affected children and 17/23 (74%) Gomel controls resulted to possess clastogenic activity irrespective of soil contamination levels. No activity was detected in the plasma of eight Pisa controls (0%). The difference between both Gomel groups and Pisa controls was highly significant (p = 0.002). A borderline, but not statistically significant correlation (p = 0.08) was observed between basal CA frequency and CF potency, which became significant (p = 0.03) when only chromosome type of aberrations was considered. We conclude that, although the presence of CFs in the plasma of these children might be partly responsible of the cytogenetic effects observed, the main source of damage has considered to be do to the previous and/or continuous exposure to environmental radiocontaminants. Tumour-affected children may represent a subset of the population either more sensitive to clastogenic damage or exposed to higher levels of contaminants.

Sister chromatid exchanges, chromosome aberrations and micronuclei in female lymphocytes: correlations with biological rhythms, miscarriages and contraceptive pill use

Our study looked at the variation in peripheral blood lymphocytes, during the menstrual cycle, of frequencies of sister chromatid exchanges (SCE) and micronuclei (MN) in 819 women and cells with aberrant chromosomes (CA) in a selected sample of 136 volunteers. We observed significant fluctuations in SCE and CA frequencies: SCEs reached a maximum value at the end of menstruation and a low at the time of ovulation, whereas CAs showed a continuous increase from the beginning of the menstrual cycle up to the time of ovulation and a progressive decrease thereafter. MN frequency did not fluctuate in a statistically significant way. No statistically significant differences in SCE, CA and MN frequencies were observed when fertile women were compared with women taking the contraceptive pill or those in menopause and no difference was found between women who had undergone physiological or surgically induced menopause. Moreover, no difference was found between women with a history of miscarriages and matched controls. These data together suggest that the natural variations in sexual hormone levels, but not those due to the contraceptive pill or their reduction at menopause, can contribute in modulating the baseline frequencies of SCEs and CAs. Moreover, these data suggest that the increased risks either of producing a chromosome imbalance in the progeny (eliciting miscarriages) or of occurrence of gynaecological diseases is not predictable by evaluating cytogenetic end-points in peripheral blood lymphocytes.

Spontaneous sister chromatid exchange and chromosome aberration frequency in humans: the familial effect

The possible effects of environmental and genetic factors on spontaneous frequencies of sister chromatid exchanges (SCEs) and cells with chromosome aberrations (CAs) in human lymphocytes were investigated by analysing 177 completed families (mother, father and at least one child). After removing the effects of methodological, biological and life-style factors by the use of multifactor analysis of variance (MANOVA), SCEs and CAs residuals were analysed by simple correlation analysis and principal component analysis. SCEs and CAs inter-familiar variability was higher than that found within families. A significant correlation was found between the average SCE frequencies shared by parents (the so-called 'midpoint parents', or 'midparent') and offspring (linear slope b=0.26+/-0.07, p<0.05), but also between mother and father (b=0.23+/-0.11, p<0.05) suggesting the presence of an effective environmental factor. The midparent-offspring correlation was found to be sustained by the mother-offspring relationship (b=0.28+/-0.08, p<0.05), being the father-offspring correlation not significant (b=0.16+/-0.11, p0.05). Concerning CAs, no statistically significant correlation between parents was found, but the strong relationship between mother and offspring was confirmed (b=0.468+/-0.11, p<0.001). The SCEs correlation between mother vs. offspring disappeared for older offspring (over 23 years old). The obtained findings strongly showed that the genetic make-up is barely detectable in the presence of domestic environment factors which are shown to play the major role in determining the interfamilial variability of SCE and CA in a general population. These results strengthen the suitability of the use of SCEs and CAs analysis in human cytogenetic surveillance for the detection of effective environmental factors.

Genetic polymorphisms influence variability in benzene metabolism in humans

The role of genetic polymorphism in modulating urinary excretion of two benzene metabolites, i.e. trans,trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (PMA), has been investigated in 59 non-smoking city bus drivers, professionally exposed to benzene via vehicle exhausts. Exposure to benzene was determined by personal passive samplers (mean +/- SD = 82.2 +/- 25.6 micrograms/m3), while internal dose and metabolic rate were evaluated by measuring urinary excretion of unmodified benzene (mean +/- SD = 361 +/- 246 ng/l), t,t-MA (mean +/- SD = 602 +/- 625 micrograms/g creatinine), and PMA (mean +/- SD = 5.88 +/- 4.76 micrograms/g creatinine). Genetic polymorphism at six loci encoding cytochrome-P450-dependent monooxygenases (CYP2E1 and CYP2D6), glutathione-S-transferases (GSTT1, GSTP1 and GSTM1) and NAD(P)H:quinone oxidoreductase (NQOR) was determined by polymerase chain reaction-based methods. No evidence emerged for a possible role of CYP2E1, GSTM1 and GSTP1 polymorphisms in determining the wide differences observed in the rate of benzene biotransformation. Conversely, a significantly higher t,t-MA urinary excretion was found to be correlated to, GSTT1 null genotype, and a significantly lower PMA excretion was detected in the subjects lacking NQOR activity and in the CYP2D6 extensive-metabolizers. Many biological (i.e. age and body burden) or lifestyle factors (i.e. rural or urban residence, use of paints and solvents, medication, alcohol and coffee intake), also taken into account as potential confounders, did not influence the correlations found. These findings suggest that CYP2D6, GSTT1 and NQOR polymorphisms contribute in explaining the metabolic variability observed in our sample. Therefore, these polymorphisms should be regarded as potential risk factors for benzene-induced adverse health effects.

Micronucleus frequency in Gomel (Belarus) children affected and not affected by thyroid cancer

Cytogenetic monitoring was carried out on a group of children from Gomel (Belarus), one of the areas most severely affected by radioactive contamination following the accident at the Chernobyl nuclear power plant, in 1986. We performed the micronucleus test (MN) in binucleated lymphocytes of 42 children (mean age: 11+/-2.34 years), 16 of whom were affected by thyroid gland tumor. Thirty healthy children living in Pisa (mean age: 14.96+/-2.17 years) were enrolled in the study as controls. Thyroid tumor affected children living in Gomel showed a statistically significant increase in the frequency of micronucleated cells as compared with the healthy children from Pisa. Moreover, a significant correlation was found between MN frequency and both the presence of tumor and higher 137Cs contamination. In addition, higher 137Cs contamination was more frequently observed in tumor affected children. These results suggest that the increased MN frequency is attributable more to 137Cs contamination rather than to the presence of the tumor itself.

Analysis of correlated data in human biomonitoring studies. The case of high sister chromatid exchange frequency cells

Sister chromatid exchange (SCE) analysis in peripheral blood lymphocytes is a well established technique that aims to evaluate human exposure to toxic agents. The individual mean value of SCE per cell had been the only recommended index to measure the extent of this cytogenetic damage until the early 1980's, when the concept of high frequency cells (HFC) was introduced to increase the sensitivity of the assay. All statistical analyses proposed thus far to handle these data are based on measures which refer to the individual mean values and not to the single cell. Although this approach allows the use of simple statistical methods, part of the information provided by the distribution of SCE per single cell within the individual is lost. Using the appropriate methods developed for the analysis of correlated data, it is possible to exploit all the available information. In particular, the use of random-effects models seems to be very promising for the analysis of clustered binary data such as HFC. Logistic normal random-effects models, which allow modelling of the correlation among cells within individuals, have been applied to data from a large study population to highlight the advantages of using this methodology in human biomonitoring studies. The inclusion of random-effects terms in a regression model could explain a significant amount of variability, and accordingly change point and/or interval estimates of the corresponding coefficients. Examples of coefficients that change across different regression models and their interpretation are discussed in detail. One model that seems particularly appropriate is the random intercepts and random slopes model.

Different effects of newly isolated saponins on the mutagenicity and cytotoxicity of the anticancer drugs mitomycin C and bleomycin in human lymphocytes

Aim of the present paper was to assess by using the in vitro micronucleus (MN) test in human lymphocytes the effect of two plant extracts isolated from Blupeurum fruticosum (saponins) on the clastogenicity and cytotoxicity of the anticancer drugs mitomycin C (MMC) and bleomycin (BLM). One saponin showed a dose-dependent MMC-induced mutagenesis inhibition together with co-genotoxic effect on BLM-treated cultures. The remaining saponin did not significantly alter MN induction of both chemotherapeutic agents whereas it enhanced BLM cytotoxicity.

Individual sensitivity to cytogenetic effects of 1,2:3,4-diepoxybutane in cultured human lymphocytes: influence of glutathione S-transferase M1, P1 and T1 genotypes

Although some blood parameters have been suggested to modulate in-vitro induction of sister chromatid exchanges by 1,2:3,4-diepoxybutane (DEB), a metabolite of 1,3-butadiene, the increased sensitivity has largely been assigned to a homozygous deletion of glutathione S-transferase T1 gene (GSTT1 null genotype). However, some DEB-sensitive individuals have been shown to be GSTT1 positive (having at least one undeleted GSTT1 allele). To examine potential causes for this overlap, we evaluated the effect of GSTM1, GSTP1, and GSTT1 genotypes, together with various life-style and blood parameters, on the DEB induction of sister chromatid exchanges and cells with chromosomal aberrations (aberrant cells) in lymphocyte cultures of 115 and 62 human donors, respectively. Our results supported the important role of the GSTT1 genotype in DEB sensitivity; 76% of cultures from GSTT1 null donors but only 4% of those from GSTT1 positive donors were DEB-sensitive, as defined by sister chromatid exchange measurements. The GSTT1 genotype also clearly affected DEB-induced aberrant cells, 92% of GSTT1 null and 8% of GSTT1 positive donors being sensitive to DEB. All individuals showing a high response to DEB in both sister chromatid exchange and aberrant cell analyses were GSTT1 null. Baseline aberrant cell measurements but not sister chromatid exchange measurements were marginally higher among GSTT1 null donors compared with GSTT1 positive donors. GSTM1 and GSTP1 genotypes had no influence on these cytogenetic end-points. Blood transaminases, gamma-glutamyl transferase, urea, creatinine and white blood cell count showed a clear negative association with DEB-induced aberrant cells, whereas wine drinkers had more aberrant cells than non-drinkers. A higher sister chromatid exchange-response to DEB was observed in lymphocytes from women and smokers than from men and non-smokers, respectively. Erythrocyte count correlated negatively with DEB-induced sister chromatid exchanges. Thus, a variety of parameters seemed to modulate the individual DEB-sensitivity together with the GSTT1 genotype. Although the known contributing factors accounted for a considerable part of individual variability in sister chromatid exchanges (59.4%) and aberrant cells (46.7%) in DEB treatment, they did not, however, fully explain the overlap in cytogenetic response between GSTT1 positive and null individuals.

Comet assay on children's leukocytes 8 years after the Chernobyl disaster

DNA damage, mainly single strand breaks, was evaluated by single cell gel electrophoresis, in leukocytes of 36 healthy and 14 thyroid cancer-affected children prior to radio-therapy. The children come from the Gomel region, one of the areas most heavily radio-contaminated by the Chernobyl fallout. In addition, leukocytes were treated with a challenge dose of bleomycin (BLM, 1.5 micrograms/ml), to assess the presence of an adaptive response (AR) potentially resulting from chronic exposure to radionuclides. As controls, 13 children living in Pisa (Italy) were enrolled in the study. Children with thyroid cancer show higher (p < 0.001) DNA damage than healthy ones. No difference was found between healthy children from Gomel and from Pisa. A reduction in the response to BLM was significantly linked to low plasma levels of FT4 hormone (p < 0.0001), to the presence of the tumor (p < 0.002), to being female (p < 0.02), and to a higher 137Cs body burden (p < 0.03).

FISH analysis of translocations in lymphocytes of children exposed to the Chernobyl fallout: preferential involvement of chromosome 10

Using whole-chromosome painting probes, we have analyzed the frequency of translocations of chromosomes 1, 3, and 10 in peripheral lymphocytes of 20 Gomel (Belarus) children, including both thyroid tumor affected and healthy individuals. Gomel was one of the most heavily radiocontaminated areas due to fallout from the Chernobyl nuclear power plant disaster. As controls, 14 healthy children from Pisa (Italy) were investigated simultaneously. Translocation rates were significantly higher in the tumor affected (1.71 +/- 0.68) and healthy Gomel children (2.69 +/- 0.50) than in the Italian controls (0.79 +/- 0.24). We also observed, in healthy Gomel children, an approximately three-fold higher frequency of chromosome 10 translocations compared to translocations affecting chromosomes 1 or 3 (P = 0.0096), a difference that was made even larger (about four fold) after correcting for chromosome size (P = 0.0009). This finding suggests a preferential involvement of chromosome 10 in translocations induced in vivo by low levels of ionizing radiation.

Use of the comet test in the evaluation of multidrug resistance of human cell lines

The comet test is a reported method for measuring DNA damage in individual mammalian cells. In the present report, the ability of this test to detect multidrug resistance (MDR) was evaluated. For this purpose, two human leukemia, well-characterized parental cell lines, HL60 and CEM, and their derived multidrug-resistant cells, HL60/DNR and CEM/VBL, were cultured with or without different anti-cancer agents. To evaluate the comet test, two DNA-damaging agents were used: daunorubicin (DNR), which is involved in MDR, and ambamustine (AMBA), which is independent from MDR. Moreover, in order to evaluate the specificity of the comet test, the activity of vinblastine (VBL), an MDR-related, DNA-independent anti-cancer drug, was also tested. Finally, the specificity of the comet test in detecting MDR was confirmed by culturing parental or resistant cells with DNR with or without the revertant agent verapamil (VER). Results confirm that the comet test is able to predict cellular chemoresistance when DNA damaging agents are tested. Finally, experiments on the role of the comet test in evaluating certain aspects of DNA repair are discussed.

Common fragile sites on human chromosomes represent transcriptionally active regions: evidence from camptothecin

Cellular processes involved in the expression of fragile sites (FS) have been investigated by studying the possible modulation of their induction by camptothecin, a specific topoisomerase I inhibitor. Expression of FS was induced by aphidicolin and then camptothecin was administered to cultures during G2 phase. Under these conditions, a very high number of chromosome aberrations were obtained: R-bands carrying FS were specifically involved in breakage and, in particular, the common FS (cFS) bands already expressed in aphidicolin-treated cultures were the most affected. These data show that the expressed FS are preferential targets of camptothecin, that is, regions where topoisomerase I-cleavable complexes are formed. This allows us to hypothesize that cFS could represent the cytogenetic expression of transcriptionally active regions. These treatments were able to induce, besides the known FS, four new FS, namely 1p34, 6p21, 6q25, and 15q15.

Sister chromatid exchange and micronucleus frequency in human lymphocytes of 1,650 subjects in an Italian population: I. Contribution of methodological factors

The influence of several methodological factors on mean values of sister chromatid exchanges (SCEs) and micronuclei (MN) in peripheral lymphocytes of 1,650 subjects was analyzed. Donors belonged to a general healthy population living in Pisa and in two nearby small cities: Cascina and Navacchio (Ca-Na). Blood samples were collected over a period of 29 months and processed in three different laboratories of the some institute. Slides were analyzed by several scorers. Our data showed that lymphocyte proliferation indexes (PIs) and baseline mean values of SCEs were affected mainly by sampling period. This factor accounted for a percentage ranging from roughly 10% (Pisa) to 20% (Ca-Na) of total SCE variance and from roughly 10% (Pisa) to 13% (Ca-Na) of total PIs variance. A marginal effect was attributable to the different laboratories involved (maximum 3% for SCEs and 7% for PIs). The sampling period variable included many sources of variability such as culture media batches, fetal calf serum, PHA, BrdUrd, and seasonality. MN counts revealed a more marked dependence on processing laboratories. This factor accounted for a percentage of roughly 10% (Pisa and Ca-Na) of total variance, while the sampling period was marginally effective (about 1-4% of total variability). Because laboratories were equipped and supplied with the same materials and consumables and technicians were rotated constantly, the only variable ascertained was represented by the three different models of CO2 incubators used for lymphocyte culturing. When "month" and "incubator" variables were considered jointly, experimental variability accounted for 15-20% of total variance, both for PIs and mean values SCEs and MN. The variability due to slide scoring was reduced by assigning each slide to five different scorers and matching low with high scorers in each group. Present data show that when the study is performed under these controlled conditions, about 20% of total interdonor variability can be explained by experimental or seasonal factors.

Detection of genetic structures at short distances in the Pisa area

The genetic structure of the population of the urban and suburban area of the town of Pisa in Tuscany in Central Italy was studied in 1,174 adults residing in 4 zones in each of 3 sampling areas, using the phenotype and gene frequencies of 9 red cell enzymes. The area investigated has a surface of about 30 km2. The enzymes were: acid phosphatase (ACP1), adenosine deaminase (ADA), adenylate kinase (AK1), esterase D (ESD), glyoxalase I (GLOI), glutamic-pyruvic transaminase (GPT), 6-phosphogluconate dehydrogenase (6-PGD), phosphogluco-mutase 1 (PGM1), and phosphoglycollate phosphatase (PGP). For the analysis of the distributions of phenotype and gene frequencies, standardised variances, kinship profiles, analysis of correspondences and isonymy were used. It was found that in this area genetic differentiation (possibly due to recent immigration) can be perceived even at short geographic distances, indicated by the significant regression of kinship on distance, especially visible in the ADA and GPT systems.

Sister chromatid exchange and micronucleus frequency in human lymphocytes of 1,650 subjects in an Italian population: II. Contribution of sex, age, and lifestyle

Sister chromatid exchange (SCE) and micronuclei (MN) analysis was carried out on 1,650 healthy individuals living in Pisa and in two nearby small cities, Cascina and Navacchio (Ca-Na). The effect of smoking on SCEs was linearly correlated with the number of cigarettes per day, and an increase of 7.3% SCEs was detectable for as few cigarettes as 1-10/day. Ex-smokers showed intermediate mean values of SCEs (8.09 +/- 1.88) in comparison with never smokers (7.54 +/- 1.61) and current smokers (8.45 +/- 1.94). Mean values of SCEs of ex-smokers decreased linearly with time of smoking cessation, reaching the mean values of never smokers within 8 years. The extent of SCE decrease was inversely proportional to the number of cigarettes previously smoked. No interaction between smoking habits and coffee or alcohol drinking on SCEs was observed. A borderline (P = 0.053) increase in mean SCE values in coffee drinkers (more than 3 cups/day) was found. The age effect on SCEs was remarkable in Ca-Na, but not in Pisa donors. Job type was not associated with significant modification of mean values of SCEs. Multiple logistic regression analysis revealed a statistically significant association between the proportion of high frequency cells (HCF) outliers and coffee consumption. Age and sex appeared to be by far the most important variables associated with modifications in MN frequency, which increased by 0.04 per thousand and 0.02 per thousand per year in males and females, respectively. Children and young donors (age < or = 40 years) showed lower MN frequency regardless of sex, whereas sex appeared to determine a significantly higher increase of MN only in females older than 40 years. In contrast, in males the MN rate by age tended to level off after the age of 30-50. MN frequencies of Pisa blue- and white-collar workers were statistically significantly higher than in students (+0.71 and +0.55 per thousand, respectively). Smoking did not determine any increase of MN frequency. A total lack of correlation (P = 0.913) between MN and SCEs was observed.

The nature of high frequency sister chromatid exchange cells (HFCs)

We employed the three-way differential staining technique (TWD), which allows SCEs to be distinguished on a per generation basis by scoring third metaphases (M3), in order to study the spontaneous levels of SCEs in normal and high frequency cells (HFCs) that occurred in the first (S1), second (S2) and third (S3) S phases. Fifty one of 900 lymphocytes from 37 healthy donors were defined as HFCs by calculating the 95th percentile of the distribution of SCEs in S1 + S2. 'Normal' cells presented almost the same number of SCEs after the first, second and third cell cycles (SCE averages of 2.43, 2.04 and 3.53 respectively). In contrast, HFCs showed a higher SCE count in S1, which decreased rapidly through the cycles and reached baseline level at S3 (SCE averages of 7.18, 4.29 and 3.45 respectively). This would suggest that the lesions responsible for the higher SCE frequency in HFCs were effectively removed after two cell cycles and strongly support the hypothesis that HFCs are lymphocytes which accumulate higher levels of DNA lesions through time.

Evaluation of DNA damage in leukocytes of ex-smokers by single cell gel electrophoresis

Single cell gel electrophoresis (SCGE), or comet assay, appears to be a promising tool to estimate DNA damage at the single cell level and it provides information on the presence of damage among individual cells. A follow-up study of 90 smokers who ceased smoking was undertaken to determine the possible decrease of DNA damage in their leukocytes. Before beginning the trial, volunteers smoked on average 26.1 +/- 8.4 cigarettes/day. Comet length did not correlate with the number of cigarettes/day or with the condensate tar content. At the end of the study, 28 volunteers had abandoned the trial, 40 volunteers relapsed into smoking at different times, but with a reduced number of cigarettes/day, whereas 22 fully succeeded in smoking cessation. Throughout the 5 sampling times, a great variability of comet length at individual level was found. However, after 1 year of follow-up, comet length means were found to be significantly shorter (p < 0.0001) in those volunteers who completely quit smoking compared to those who relapsed into smoking (27.2 +/- 1.6 vs. 31.9 +/- 5.1 microns, respectively), irrespective of the amount of cigarettes previously smoked. No effect of age or sex was found. Six months later, these results were confirmed by a further study carried out on a reduced sample of volunteers. The present data strongly suggest that, in spite of the great variability observed, 1 year of smoking cessation is associated with a significant reduction of DNA damage in circulating leukocytes.

Age-related increase of baseline frequencies of sister chromatid exchanges, chromosome aberrations, and micronuclei in human lymphocytes

Intra- and interindividual variations of baseline frequencies of cytogenetic end points in lymphocytes of human populations have been reported by various authors. Personal characteristics seem to account for a significant proportion of this variability. Several studies investigating the role of age as a confounding factor in cytogenetic biomonitoring found an age-related increase of micronucleus (MN) frequency, whereas contradictory results were reported for chromosomal aberrations (CAs) and sister chromatid exchanges (SCEs). We have quantitatively evaluated the effect of age on SCE, CA, and MN through the analysis of a population sample that included data from several biomonitoring studies performed over the last few decades in 12 Italian laboratories. The large size of the data set, i.e., more than 2000 tests for each end point, allowed us to estimate the independent effect of age, taking into account other covariates, such as sex, smoking habits, occupational exposure, and inter- and intralaboratory variability. A greater frequency of the mean standardized values by increasing of age was observed for all of the end points. A leveling off was evident in the last age classes in the trend of MN frequencies. Frequency ratios (FRs), which express the increase of the cytogenetic damage with respect to the first age classes, i.e., 1-19 years, were estimated using Poisson regression analysis after adjustment for the potential confounding factors and confirmed the increasing trend by age class for all three end points. The most dramatic increase was observed for MN, with a FR that approaches the value of 2 at the age class 50-59 (FR, 1.97; 95% confidence interval, 1.43-2.71) and remains substantially unchanged thereafter. The trend of FRs for CA is more homogeneous, with a constant rise even in the older classes, whereas the frequency of SCE increases with age to a lesser extent, reaching a plateau in the age class 40-49 and the maximum value of FR in the age class over 70 (FR, 1.14; 95% confidence interval, 1.07-1.23). In conclusion, our results point to an age-related increase of the chromosome damage in lymphocytes and emphasize the need to take into account the potential confounding effect of this variable in the design of biomonitoring studies based on chromosome damage.

Modulating factors of individual sensitivity to diepoxybutane: chromosome aberrations induced in vitro in human lymphocytes

Peripheral blood lymphocytes from a sample of 62 randomly selected donors were analysed for spontaneous and diepoxybutane (DEB)-induced chromosomal aberrations (CA). These individuals were part of a larger sample of 122 subjects whose DEB responsiveness was evaluated by means of sister chromatid exchange (SCE) analysis. Confounding factors (such as smoking, wine and coffee consumption, occupation and haematological factors) were analysed for their effect on individual DEB-responsiveness, but no statistically significant associations were observed. Interestingly, a bimodal distribution of aberrant cell frequencies was clearly detectable, showing the existence of DEB-sensitive subjects belonging to the second mode (CA frequencies > 19%). When responsiveness evaluated by means of CA induction was compared with SCE responsiveness, it was noted that all SCE-inducible subjects (> 110.9 SCEs/cell) belonged to the second mode of CA frequency distribution. On the other hand, highly CA inducible individuals did not necessarily show a higher SCE-response, although their DEB-induced SCE frequencies were above average (92 SCEs/cell). DEB-induced CA frequency correlated with baseline levels, indicating that DEB-sensitive individuals also showed higher spontaneous chromosome damage (3.6 versus DEB-resistant 2%, P < 0.05). Finally, when simple and multiple regression analyses were carried out, DEB-sensitivity appeared negatively related to haematic concentrations of proteins and uric acid (intercept 0.131 +/- 0.011, slope -0.029 +/- 0.0116, r = -0.39; P < 0.01), probably due to its antioxidant activity. This finding confirmed previous observations on the scavenger activity of plasma factors on DEB mutagenicity.

Modulating factors of individual sensitivity to diepoxybutane: sister chromatid exchanges induced in vitro in human lymphocytes

Spontaneous and diepoxybutane (DEB)-induced sister chromatid exchanges (SCEs) were examined in cultured peripheral lymphocytes (PBL) from 122 healthy donors. SCE-inducing activity under defined experimental conditions and individual sensitivity to genotoxic stress were assessed. SCE means distribution appeared asymmetrical, identifying about 22% of subjects characterized by a 'high-respondent' phenotype with more than 111 SCEs/cell. Confounding factors, such as smoking habit, wine and coffee consumption, work activity and hematological factors, showed a limited capacity to affect individual SCE responsiveness, however hemoglobin and uric acid seemed to antagonize DEB genotoxicity.

In vivo cytogenetic effects of natural humic acid

As humic compounds are naturally widespread in the environment and present in surface water, studies on their genotoxicity are justified. Humic acid (HA) has not been demonstrated to be genotoxic either in vitro or in vivo. In the present paper we investigated its activity both in intestinal and bone marrow cells following a single dose (100 mg/kg b.w. corresponding to 0.5 ml per animal of an aqueous solution of 4 g/l) of HA administered to mice by gastric intubation, to mimic the most likely route of human exposure. HA induced structural and, in particular, numerical chromosome abnormalities in intestinal cells. A marginal, non-significant induction of aneuploidy was also found in bone marrow cells.

Chromosome aberrations in humans in relation to site of residence

Baseline frequencies of chromosome aberrations (CAs) were assessed in three samples of healthy individuals, 60 living in a rural area (Po Delta), 134 in Pisa downtown and 116 in Cascina, a small town near Pisa, Italy. The three groups were similar for average age, sex ratio, smoking, drinking habit, and occupation. Multifactor ANOVA showed that CA frequencies increased significantly with age (p < 0.0001 excluding and including gaps), and with smoking habit (p = 0.0045 including gaps; p = 0.04 excluding gaps). Gender, drinking habit and occupation exerted no statistically significant effects. Multifactor ANOVA showed also a significant effect of the site of residence on the frequency of the CA, including gaps (p = 0.0003) and excluding gaps (p = 0.03). The CA frequency of the Pisa samples was statistically significantly higher than that of the Po Delta samples. Air pollution was considered to be a possible factor in determining the observed differences among the sites of residence, as levels of air pollutants (SO2 and TSP, total suspended articles) were more elevated in Pisa and Cascina than in the Po Delta. In addition, respiratory symptoms used as indirect indicators of air pollution at individual level were significantly more frequent in the Pisa population than in Cascina or in the Po Delta. These findings might support the hypothesis that air-pollution levels, even within E.E.C. (European Economic Community) air-quality standards, may influence baseline CA frequencies.

Mutagenic activity of some coal-derived humic compounds evaluated by the Ames test

Two coal-derived humic substances (Sulcis and South Africa, Eniricerche, Italy) have been evaluated for their mutagenic activity on TA98 and TA100 Salmonella typhimurium strains, either in presence or in absence of metabolic activation (S9). Both compounds showed no effect on the two strains, as observed with natural humic acid (Fluka). After chlorination, coal-derived humic acids induced a strong dose-related increase in the number of revertants on TA100 without S9, whose extent was directly proportional to the chlorination ratios. Such effect was completely suppressed when a sodium thiosulfate solution (10%) was added at the end of the chlorination period (about 90 h). The analogies with natural humic acid mutagenicity are discussed.

Repeated analysis of sister chromatid exchange induction by diepoxybutane in cultured human lymphocytes: effect of glutathione S-transferase T1 and M1 genotype

Spontaneous and diepoxybutane (DEB)-induced sister-chromatid exchanges (SCEs) were examined in whole-blood lymphocyte cultures of 3 men and 4 women. A strong increase in mean number of SCEs per cell with increasing DEB concentrations (0, 2, and 4 microM) was observed in cultures of all subjects, but 3 of the donors were clearly more sensitive than the others. The SCE measurements were repeated 2-6 times per donor over a period of 55 months to assess the stability of the individual SCE response. The results showed that SCE induction by DEB was steady in the individuals during the follow-up at each DEB dose, with no significant differences among the repeated experiments. At 4 microM DEB, the DEB-sensitive and -resistant donors could be reliably be differentiated from each other in all trials. As DEB-sensitivity has been suggested to be due to the lack of glutathione S-transferase (GST) T1, the donors were genotyped for the presence of GSTT1 and GSTM1 genes. The 3 individuals found to be DEB-sensitive were all of the GSTT1 null genotype, whereas the 4 DEB-resistant donors were GSTT1 positive, which supported the role of the GSTT1 gene in determining DEB-sensitivity. Three of the DEB-resistant and none of the DEB-sensitive had the GSTM1 null genotype. Thus, the lack of the GSTM1 gene was not associated with the DEB-sensitivity trait. In conclusion, the present findings show that individual SCE responses to treatment of cultured human lymphocytes with DEB can reliably be reproduced in repeated trials. The results confirm that the GSTT1 gene but not the GSTM1 gene is important in determining individual sensitivity to the in vitro genotoxicity of DEB.

Persistence of 4-nitroquinoline-1-oxide induced lesions in human lymphocytes

Liquid holding (LH) recovery was matched with three-way differential staining (TWD) to assess the reduction of damage induced in DNA following treatment with 4-nitroquinoline-1-oxide (4NQO) in resting (GO) lymphocytes. Human peripheral lymphocytes (HPL) from three donors were used to evaluate lesion persistence and individual repair capacity. Our data are in contrast to those for diepoxybutane (Ponzanelli et al., 1995) and suggest that LH recovery is completely inefficient in removing 4NQO induced lesions, which are only partially repaired after one cell cycle.