G. Stephanou

Bio: G. Stephanou is an academic researcher from University of Patras. The author has contributed to research in topics: Micronucleus test & Chromosome breakage. The author has an hindex of 16, co-authored 37 publications receiving 761 citations.

Chromosomal aberrations, sister-chromatid exchanges, cells with high frequency of SCE, micronuclei and comet assay parameters in 1,3-butadiene-exposed workers

Abstract: The association of occupational exposure to 1,3-butadiene (BD) and induction of cytogenetic damage in peripheral lymphocytes was studied in 19 male workers from a monomer production unit and 19 control subjects from a heat production unit. The exposure to BD was measured by passive personal monitors. The following biomarkers were used: chromosomal aberrations (CA), sister chromatid exchanges (SCE), cells with a high frequency of SCE (HFC), micronuclei, comet assay parameters like tail length (TL) and percentage of DNA in tail [ T (%)] and polymorphisms of GSTM1 and GSTT1 genotypes. BD exposure with a median value of 0.53 mg/m 3 (range: 0.024–23.0) significantly increased (a) the percentage of cells with chromosomal aberrations in exposed vs. control groups (3.11% vs. 2.03%, P P P

Human cytogenetic biomonitoring of occupational exposure to 1,3-butadiene

Abstract: The association of occupational exposure to 1,3-butadiene and chromosomal damage in peripheral blood lymphocytes was studied in 40 workers from two production facilities. Control persons, 30 in all, were chosen from other departments of the same plants, and they were roughly matched for age and smoking habits. The exposure levels to ambient butadiene were measured both by personal sampling using diffuse monitors and by stationary sampling at production and handling sites. Chromosome aberrations (CA) micronuclei (MN) and sister-chromatid exchanges (SCE) in peripheral lymphocytes were analyzed as markers of exposure. Smoking had a slight effect on the frequency of MN, and the mean frequency of SCEs was also higher in smokers than in non-smokers. No effect of smoking, however, was seen in relation to chromosomal aberrations. No exposure related effects were seen in any of the three cytogenetic endpoints in either of the butadiene production plants, representing typical low (below 3 ppm) exposure levels of the butadiene manufacturing industry.

Interactions between CYP1A1 polymorphisms and exposure to environmental tobacco smoke in the modulation of lymphocyte bulky DNA adducts and chromosomal aberrations.

Abstract: CYP1A1 plays an important role in the metabolic activation of polycyclic aromatic hydrocarbons (PAH), carcinogenic components of air pollution. The influence of CYP1A1 genotype (*2A, *2B and *4) on the levels of lymphocyte bulky DNA adducts and the frequency of cells with aberrant chromosomes was assessed in 194 non-smoking subjects in whom recent exposure to environmental tobacco smoke (ETS) and airborne particulate-associated PAH were measured during two consecutive seasons (winter and summer). While CYP1A1*4 had no consistent effect on either biomarker of genetic damage, the levels of both biomarkers responded in a parallel fashion to changes in exposure/CYP1A1*2A genotype combinations during both seasons. Specifically, the levels of both biomarkers were increased in carriers of at least one CYP1A1*2A allele, as compared with CYP1A1*1 homozygotes, in subjects with ETS exposures >0.8 h/day during the previous 4 days and mean personal exposure to benzo[a]pyrene <0.9 ng/m 3 during the previous 24 h (all P < 0.05). Outside these exposure limits the differential effect in CYP1A1*2A variants was lost. Although the numbers of subjects with the CYP1A1*2B polymorphism was small, the same trend appeared to be followed in this case. These effects are interpreted as resulting from differential induction of CYP1A1 expression in CYP1A1*2A and CYP1A1*2A/*2B carriers by components of ETS-polluted air at levels of exposure readily suffered by large segments of the general population and suggest that subjects with these genotypes may have increased susceptibility to the genotoxic effects of ETS.

Heat-shock proteins, molecular chaperones, and the stress response: evolutionary and ecological physiology

Abstract: Molecular chaperones, including the heat-shock proteins (Hsps), are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Hsps have received the most attention in model organisms undergoing experimental stress in the laboratory, and the function of Hsps at the molecular and cellular level is becoming well understood in this context. A complementary focus is now emerging on the Hsps of both model and nonmodel organisms undergoing stress in nature, on the roles of Hsps in the stress physiology of whole multicellular eukaryotes and the tissues and organs they comprise, and on the ecological and evolutionary correlates of variation in Hsps and the genes that encode them. This focus discloses that (a) expression of Hsps can occur in nature, (b) all species have hsp genes but they vary in the patterns of their expression, (c) Hsp expression can be correlated with resistance to stress, and (d) species' thresholds for Hsp expression are correlated with levels of stress that they naturally undergo. These conclusions are now well established and may require little additional confirmation; many significant questions remain unanswered concerning both the mechanisms of Hsp-mediated stress tolerance at the organismal level and the evolutionary mechanisms that have diversified the hsp genes.

Allergic Rhinitis and Its Impact on Asthma

Abstract: Authors Jan L. Brozek, MD, PhD – Department of Clinical Epidemiology & Biostatistics and Medicine, McMaster University, Hamilton, Canada Jean Bousquet, MD, PhD – Service des Maladies Respiratoires, Hopital Arnaud de Villeneuve, Montpellier, France, INSERM, CESP U1018, Respiratory and Environmental Epidemiology Team, France, and WHO Collaborating Center for Rhinitis and Asthma Carlos E. Baena-Cagnani, MD – Faculty of Medicine, Catholic University of Cordoba, Cordoba, Argentina Sergio Bonini, MD – Institute of Neurobiology and Molecular Medicine – CNR, Rome, Italy and Department of Medicine, Second University of Naples, Naples, Italy G. Walter Canonica, MD – Allergy & Respiratory Diseases, DIMI, Department of Internal Medicine, University of Genoa, Genoa, Italy Thomas B. Casale, MD – Division of Allergy and Immunology, Department of Medicine, Creighton University, Omaha, Nebraska, USA Roy Gerth van Wijk, MD, PhD – Section of Allergology, Department of Internal Medicine, Erasmus Medical Centre, Rotterdam, the Netherlands Ken Ohta, MD, PhD – Division of Respiratory Medicine and Allergology, Department of Medicine, Teikyo University School of Medicine, Tokyo, Japan Torsten Zuberbier, MD – Department of Dermatology and Allergy, Charite Universitatsmedizin Berlin, Berlin, Germany Holger J. Schunemann, MD, PhD, MSc – Department of Clinical Epidemiology & Biostatistics and Medicine, McMaster University, Hamilton, Canada

The HUman MicroNucleus Project--An international collaborative study on the use of the micronucleus technique for measuring DNA damage in humans.

Abstract: The International Collaborative Project on Micronucleus Frequency in Human Populations (HUMN) was organized to collect data on micronucleus (MN) frequencies in different human populations and different cell types. The test procedures considered by this project are assays using human lymphocytes (cytokinesis-block method), exfoliated epithelial cells, and other cell types. Data (including descriptions of the populations monitored, detailed test protocols, and test results) are being obtained from a large number of laboratories throughout the world and are being entered into a unified database. The information will be used to: (1) determine the extent of variation of 'normal' values for different laboratories and the influence of other factors potentially affecting baseline MN frequency, e.g., age, gender and life-style; (2) provide information on the effect of experimental protocol variations on MN frequency measurements; (3) design and test optimal protocols for the different cell types; and (4) determine the extent to which MN frequency is a valid biomarker of ageing and risk for diseases such as cancer.