Lack of association between GSTT1 polymorphism and endogenous or benzo[a]pyrene-induced sister chromatid exchanges as analyzed in metaphase or G2-phase lymphocytes.

The objectives of the present work are (1) to verify whether genetic polymorphism in the detoxification gene GSTT1 influences the endogenous sensitivity in terms of sister chromatid exchanges (SCEs)/cell in healthy donors and (2) to test whether in vitro exposure to B[a]P in terms of SCEs/cell can be associated with polymorphism of GSTT1 gene. The presence or absence of the homozygous deletion in GSTT1 gene was determined in peripheral blood cells using multiplex-PCR. For SCEs quantitation, the cytogenetic method used thus far is based on the analysis in metaphase chromosomes. Consequently, G2-arrested cells are not included in the analysis. To overcome this shortcoming of the conventional method, we applied here SCE analysis in G2-phase prematurely condensed chromosomes (G2-PCCs) induced by calyculin-A, using a modified fluorescence-plus-Giemsa staining protocol. Compared to metaphase, a statistically significant increase in the yield of SCEs was notified in the G2-phase analysis after 48 h exposure of peripheral blood lymphocytes to 0.01-1 mM B[a]P, in both GSTT1-positive and -null donors. Therefore, the analysis of SCEs in the G2-phase using calyculin-A induced PCC methodology was shown to be more sensitive compared to the analysis at the metaphase level. Nevertheless, the results obtained do not show an association between the GSTT1 polymorphism with increased endogenous and/or B[a]P-induced SCE-frequencies in peripheral blood lymphocyte chromosomes in vitro. These results highlight not only the effect of B[a]P on cell cycle kinetics but also they demonstrate that conventional cytogenetic analysis at metaphase underestimates the cytogenetic effects of chemicals that delay cell cycle progression in G2-phase.

Occupational injuries in Greece (1938-1955): history of medicine and descriptive epidemiology.

AIM: To describe the longitudinal trends in the rates of total and fatal occupational accidents in Greece during 1938-1955. MATERIAL AND METHODS: Information on occupational injuries have been provided from the yearly reports of the Organization of Social Insurances (1938-1955) and on population data from the tables of National Statistic Agency. Bio-statistical analysis was performed by the use of SPSS software and Stat-Calc of Epi Info. RESULTS: The evolution of the longitudinal trend of occupational accidents has revealed a biphasic character, with a decreasing trend during 1938-1945 and an increasing trend during 1946-1955. The phenomenon was obvious in both sexes and in all age groups. On the contrary fatal occupational injuries increased across the period 1938-1945 and subsequently decreased. These temporal trends can be interpreted on the light of the important reduction in the level of economic activity during the second world war and the subsequent gradual recovery in the post war period. CONCLUSION: The biphasic characteristics of the occupational accidents longitudinal trend seems to be influenced by historical factors. Important lessons were learnt from the period of war. The decrease of the rate of total occupational accidents does not necessary reflect a satisfactory level of safety at work. The level of the economic activity, the efficiency of the registration and prevention agencies play a role. In addition, the rate of fatal injuries has a critical role in benchmarking national occupational health performance.

Clonal chromosome rearrangements in hairy cell leukemia: personal experience and review of literature.

Cytogenetic studies in hairy cell leukemia (HCL) are rare. In the present report, cytogenetic investigations were performed on marrow cells obtained from 21 HCL male patients with a mean age of 57 years and active disease. Karyotypic analysis was successful in 18 of the 21 patients, either at diagnosis or in relapse after treatment with IFNa. Clonal chromosome abnormalities were detected in eight of 18 cases. The chromosome most frequently involved in the rearranged karyotypes was chromosome 14. Results are discussed with respect to 79 abnormal HCL cases obtained from an extensive review of the literature from 1978 to 2000.

Increased G2 chromosomal radiosensitivity in cancer patients: the role of cdk1/cyclin-B activity level in the mechanisms involved.

PURPOSE: To test the hypothesis that deficient DNA repair as measured by increased G2 chromosomal radiosensitivity results from up-regulation of cdk1/cyclinB and cell cycle control mechanisms during the G2 to M transition. MATERIALS AND METHODS: A total of 185 cancer patients and 25 normal individuals were tested for G2 chromosomal radiosensitivity. The chromatid breaks were analysed in metaphase using the G2 assay or directly in G0 and G2 phase using premature chromosome condensation (PCC). The activity of cdk1/cyclinB, a key regulator of the G2 to M-phase transition, was measured by histone H1 kinase activity and correlated with the development of chromatid breaks after irradiation of cell lines in vitro. RESULTS: Based on the G2 assay, cancer patients on average showed increased chromosomal radiosensitivity above controls. When the analysis was carried out directly in G0 or G2 lymphocytes using PCC, no differences in the induction of chromosomal damage and its repair were observed between G2 assay-sensitive and G2-normal donors. Using the G2 assay to test G2 radiosensitivity in various cell lines, it was found that the higher the cdk1/cyclinB activity level of the cell line tested, the higher the yield of chromatid breaks scored. Furthermore, when mitotic cells from these cell lines were used for PCC induction in irradiated G2 lymphocytes it was observed that the higher the cdk1/cyclinB activity level of mitotic cells used, the higher was the induced yield of chromatid breaks. CONCLUSION: The cdk1/cyclin-B activity levels during the G2 to M transition impair DNA repair processes and play a major role in the yield of chromatid breaks induced after G2-irradiation. Regulation of cdk1/cyclinB complex activity rather than deficient repair enzymes of DNA damage may underlie the mechanisms of G2 radiosensitivity.

Determination of urinary thymidine glycol using affinity chromatography, HPLC and post-column reaction detection: a biomarker of oxidative DNA damage upon kidney transplantation.

Reactive oxygen species are generated during ischaemia-reperfusion of tissue. Oxidation of thymidine by hydroxyl radicals (HO) leads to the formation of 5,6-dihydroxy-5,6-dihydrothymidine (thymidine glycol). Thymidine glycol is excreted in urine and can be used as biomarker of oxidative DNA damage. Time dependent changes in urinary excretion rates of thymidine glycol were determined in six patients after kidney transplantation and in six healthy controls. A new analytical method was developed involving affinity chromatography and subsequent reverse-phase high-performance liquid chromatography (RP-HPLC) with a post-column chemical reaction detector and endpoint fluorescence detection. The detection limit of this fluorimetric assay was 1.6 ng thymidine glycol per ml urine, which corresponds to about half of the physiological excretion level in healthy control persons. After kidney transplantation the urinary excretion rate of thymidine glycol increased gradually reaching a maximum around 48 h. The excretion rate remained elevated until the end of the observation period of 10 days. Severe proteinuria with an excretion rate of up to 7.2 g of total protein per mmol creatinine was also observed immediately after transplantation and declined within the first 24 h of allograft function (0.35+/-0.26 g/mmol creatinine). The protein excretion pattern, based on separation of urinary proteins on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), as well as excretion of individual biomarker proteins, indicated nonselective glomerular and tubular damage. The increased excretion of thymidine glycol after kidney transplantation may be explained by ischaemia-reperfusion induced oxidative DNA damage of the transplanted kidney.

Acute intoxication with trichloroethene: clinical symptoms, toxicokinetics, metabolism, and development of biochemical parameters for renal damage.

The present study reports on a 17-year-old male who ingested approximately 70 ml trichloroethene (TRI) in a suicide attempt. The patient developed fever, tremor, general motor restlessness, and sinus tachycardia and lost consciousness 5 h after poisoning. After 5 days of intubation under narcosis with forced hyperventilation and diuresis he regained consciousness. During this period blood and urine were collected and TRI and its metabolites were quantified. The highest concentration of TRI in blood was detected 13 h after ingestion. Trichloroethanol and trichloroacetic acid, metabolites of the cytochrome P450-mediated pathway, and N-acetyl-S-(1, 2-dichlorovinyl)-l-cysteine and N-acetyl-S-(2, 2-dichlorovinyl)-l-cysteine from the glutathione-dependent pathway of TRI were quantified in urine samples. Besides these known metabolites in humans, chloroacetic acid and dichloroacetic acid were identified for the first time in urine of a human exposed to TRI. Although the patient exhibited normal levels of glucose and total protein in urine, excretion of alpha1- and beta2-microglobulin as well as beta-NAG was significantly increased. In addition to these typical markers of selective tubule damage, analysis of the urinary protein pattern by SDS-PAGE revealed increased excretion of several low-molecular-mass proteins between 10,000 and 50,000 Da, clearly indicating tubular damage. Based on the elucidated glutathione-dependent mechanism for the nephrotoxicity of TRI, activation of the formed S-conjugates by beta-lyases to reactive intermediates may account for the observed renal effects after a single, high dose of TRI.

Effects of lead on the somatic growth of children.

Studies on the effects of lead on the somatic growth of children are limited and contradictory. The authors investigated the adverse effects of blood lead concentration on the somatic growth of primary-school-age children. In this study, there was a total of 522 children, aged 6-9 y, who resided in three areas of Greece (i.e., Loutraki, Lavrion, and Elefsina). The medical evaluation included medical history; physical examination; and measurements of height, head circumference, and chest circumference. The authors also evaluated dietary information, socioeconomic status, and height of parents. The authors conducted laboratory tests for hematological parameters and blood lead levels. The mean blood lead level was 12.3 microg/dl (standard deviation = 8.9 microg/dl), and levels ranged from 1.3 microg/dl to 51.2 microg/dl. There were negative monotonic relationships between growth parameters and blood lead levels, even after the authors allowed for confounding effects. An increase in blood lead level of 10 microg/dl was associated with a decrease of (a) 0.33 cm in head circumference (95% confidence interval = 0.12, 0.55; p = .002); (b) 0.86 cm in height (95% confidence interval = 0.14, 1.16; p = .020); and (c) 0.40 cm in chest circumference (95% confidence interval = -0.22, 1.02; p = .207). These findings led the authors to conclude that a decrease in growth in children may be associated with blood lead concentrations.

Preexistence of chronic tubular damage in cases of renal cell cancer after long and high exposure to trichloroethylene.

Substantially more cases of tubular damage were found among renal cell carcinoma patients who had been exposed to high levels of trichloroethylene over many years than among renal cell carcinoma patients who had not been exposed to trichloroethylene. This supports the hypothesis (Goeptar et al. 1995) that chronic tubular damage may be regarded as a necessary precondition for trichloroethylene to exert a nephrocarcinogenic effect. The findings also indicate that the urine protein patterns identified with SDS-PAGE may represent a valuable parameter for effect biomonitoring of persons exposed to high levels of trichloroethylene over many years.

Selenium-mediated inhibition of transcription factor NF-kappa B and HIV-1 LTR promoter activity.

The eukaryotic transcription factor NF-kappa B is involved in the inducible expression of various inflammatory genes as well as in HIV-1 replication. Activation of NF-kappa B is induced by prooxidants and several stimuli eliciting oxidative stress, such as cytokines, lipopolysaccharide, UV irradiation and other mediators. Various antioxidants inhibit NF-kappa B activation in response to these stimuli. In this study, we have investigated the effects of selenium, an integral component of glutathione peroxidase (GPX), on NF-kappa B activation. In selenium-deprived Jurkat and ESb-L T lymphocytes, supplementation of selenium led to a substantial increase of GPX activity. Analysis of DNA binding revealed that NF-kappa B activation in response to TNF was significantly inhibited under these conditions. Likewise, reporter gene assays using luciferase constructs driven by the HIV-1 long terminal repeat showed a dose-dependent inhibition of NF-kappa B controlled gene expression by selenium. The effects of selenium were specific for NF-kappa B, since the activity of the transcription factor AP-1 was not suppressed. These data suggest that selenium supplementation may be used to modulate the expression of NF-kappa B target genes and HIV-1.