DNA oxidation by potassium bromate; a direct mechanism or linked to lipid peroxidation?

Following incubation of calf thymus DNA with potassium bromate (KBrO3) and glutathione (GSH), a statistically significant increase in the concentration of 8-oxodeoxyguanosine (8-oxodG) relative to deoxyguanosine was measured. This was GSH-dependent and was associated with loss of GSH during incubation. In contrast, 8-oxodG was not found to be elevated significantly in either total tissue DNA or mitochondrial DNA isolated from Sprague-Dawley rat kidney perfused in situ with KBrO3 (5 mM) for 15 min or 1 h.

Lipid peroxidation-induced etheno-DNA adducts in the liver of patients with the genetic metal storage disorders Wilson's disease and primary hemochromatosis.

To assess DNA damage caused by lipid peroxidation due to copper and iron storage disorders in the human liver, the formation of the etheno adducts 1,N6-ethenodeoxyadenosine (epsilon dA) and 3,N4-ethenodeoxycytine (epsilon dC) was measured in liver DNA from normal subjects and from patients with Wilson's disease (WD) and primary hemochromatosis. The mean epsilon dA and epsilon dC levels per 10(9) parent nucleotides in normal liver were 19.3 +/- 4.

Etheno-DNA base adducts as tools in human cancer aetiology and chemoprevention.

Etheno adducts in DNA are formed from the carcinogens vinyl chloride and urethane, and also from products of lipid peroxidation (LPO), such as trans-4-hydroxy-2-nonenal. Using an ultrasensitive detection method, the formation of etheno-DNA adducts in the liver was demonstrated in LEC rats (a strain with hereditary abnormal copper metabolism) that develop hepatitis and hepatocellular carcinoma. Wilson's disease and primary haemochromatosis are human genetic disorders that cause copper or iron accumulation resulting in a high risk for primary liver cancers.

Cytotoxic and antimalarial alkaloids from Brunsvigia littoralis.

Four known alkaloids, lycorine (1), 1,2-di-O-acetyllycorine (2), ambelline (3), and crinine (4) were isolated from the bulbs of Brunsvigia littoralis (Amaryllidaceae). 1H- and 13C-NMR spectra of 2 were completely assigned by means of 1D- and 2D-NMR techniques. The alkaloids (1-4) together with the synthesised 11-O-acetylambelline (3a) and 3-O-acetylcrinine (4a) were tested for antimalarial activity with two strains of cultured Plasmodium falciparum and for cytotoxicity with BL6 mouse melanoma cells.

High dietary omega-6 polyunsaturated fatty acids drastically increase the formation of etheno-DNA base adducts in white blood cells of female subjects.

Lipid peroxidation generates reactive aldehydes such as trans-4-hydroxy-2-nonenal and malonaldehyde, which form promutagenic exocyclic DNA adducts in human cells and may contribute to diet-related cancers. Using ultrasensitive detection methods, analysis of WBC DNA from volunteers in a dietary study revealed that high intake of omega-6 polyunsaturated fatty acids increased malonaldehyde-derived adducts in male and female subjects. In contrast, etheno adducts (1,N6-ethenodeoxyadenosine; 3,N4-ethenodeoxycytidine) were not elevated in males but were, on average, 40 times higher in females, displaying a huge intersubject variation in lipid peroxidation-derived DNA damage.

DNA adducts and chronic degenerative disease. Pathogenetic relevance and implications in preventive medicine.

Chronic degenerative diseases are the leading causes of death in developed countries. Their control is exceedingly difficult due to their multiplicity and diversity, the interconnection with a network of multiple risk factors and protective factors, the long latency and multistep pathogenesis, and the multifocal localization. Adducts to nuclear DNA are biomarkers evaluating the biologically effective dose, reflecting an enhanced risk of developing a mutation-related disease more realistically than the external exposure dose.

Detection of 1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxycytidine by immunoaffinity/32P-postlabelling in liver and lung DNA of mice treated with ethyl carbamate (urethane) or its metabolites.

The capacity of the chemical carcinogen ethyl carbamate (EC, urethane) and its metabolites vinyl carbamate (VC) and vinyl carbamate epoxide (VCO) to form ethenobases was studied in liver and lung DNA of 12-day-old and adult CD-1, B6C3F1, C3H/HeJ and C57BL/6J mice. Following single and multiple doses of EC, VC or VCO, the formation of 1,N6-ethenodeoxyadenosine (epsilon dA) and 3,N4-ethenodeoxycytidine (epsilon dC) was quantified by an immunoaffinity chromatography/32P-postlabelling technique. Both etheno adducts were detected in untreated control DNA samples from liver and lung in the range of 2-15 adducts/10(9) parent nucleotides.

Formation and accumulation of DNA ethenobases in adult Sprague-Dawley rats exposed to vinyl chloride.

DNA ethenobases are promutagenic lesions formed by carcinogens such as vinyl chloride (VC). Their formation was investigated in 6-week old, male Sprague-Dawley rats exposed to 500 p.p.

Ion chromatography of amylamine and tert.-butylamine in pharmaceuticals.

Ion chromatographic (IC) methods have been developed for the assay of amylamine in BMS-181 866-02 and tert.-butylamine (TBA) in BMS-188 494-04. BMS-181 866-02 is the penultimate intermediate in the synthesis of a novel thromboxane antagonist, BMS-180 291-02, which is undergoing clinical trials.

DNA damage and repair in mutagenesis and carcinogenesis: implications of structure-activity relationships for cross-species extrapolation.

Previous studies on structure-activity relationships (SARs) between types of DNA modifications and tumour incidence revealed linear positive relationships between the log TD50 estimates and s-values for a series of mostly monofunctional alkylating agents. The overall objective of this STEP project was to further elucidate the mechanistic principles underlying these correlations, because detailed knowledge on mechanisms underlying the formation of genotoxic damage is an absolute necessity for establishing guidance values for exposures to genotoxic agents. The analysis included: (1) the re-calculation and further extension of TD50 values in mmol/kg body weight for chemicals carcinogenic in rodents.

Relationship of personality, environmental, and DICA variables to adolescent hopelessness: a neural network sensitivity approach.

Objective: This study identified critical factors from a set of psychiatric diagnoses, personality traits, and family and social support variables that relate to hopelessness in adolescents.

Method: One hundred fifty adolescents were selected in a systematic sample from 1,700 high school students; they completed the Millon Adolescent Personality Inventory, the Parental Bonding Questionnaire, the Social Support Questionnaire, the Hopelessness Scale for Children and were interviewed by trained clinicians on the Diagnostic Interview for Children and Adolescents. Selected variables were chosen for a back-propagation neural network model and for subsequent sensitivity and statistical analysis.

Copper-dependent formation of miscoding etheno-DNA adducts in the liver of Long Evans cinnamon (LEC) rats developing hereditary hepatitis and hepatocellular carcinoma.

Formation of etheno-DNA adducts in the liver was investigated in Long Evans cinnamon (LEC) rats, a Long Evans strain with hereditary abnormal copper metabolism, which develop spontaneous hepatitis and later hepatocellular carcinoma. Using an ultrasensitive immunoaffinity/32P-postlabeling assay (J. Nair et al.

Endogenous formation of nitrosamines and oxidative DNA-damaging agents in tobacco users.

One-third of all cancers worldwide can be attributed to various tobacco habits. Both in tobacco smoke and smokeless tobacco, carcinogenic N-nitroso compounds (NOC) are implicated as DNA-damaging agents in cancers of the aerodigestive tract and the pancreas. The exposure from nitrosamines in certain types of tobacco use such as "toombak" in Sudan could be as high as a few milligrams per day.

The absence of genetic markers for streptomycin and rifampicin resistance in Mycobacterium avium complex strains.

Mycobacterium avium, Mycobacterium intracellulare complex (MAC) bacilli are an important cause of bacteraemia in AIDS patients but treatment is complicated by their resistance to the usual antimycobacterial agents. In this study of 20 strains of MAC none was found to have the mutations associated with resistance to rifampicin and streptomycin in M. tuberculosis suggesting that MAC have unique mechanisms for resistance to these agents.

A highly immunogenic putative Mycobacterium kansasii lipoprotein.

The resurgence of tuberculosis, the emergence of multiple drug resistant tuberculosis, and the increasing prevalence of mycobacterial disease in AIDS patients have increased the importance of defining new mycobacterial antigens that can be utilized in the development of improved diagnostic reagents and more effective vaccines. In this report, a highly immunogenic Mycobacterium kansasii protein (MK35) and the gene encoding this antigen were characterized. MK35 gene probes reacted with genomic DNA from M.

Ortho- and meta-tyrosine formation from phenylalanine in human saliva as a marker of hydroxyl radical generation during betel quid chewing.

The habit of betel quid chewing, common in South-East Asia and the South Pacific islands, is causally associated with an increased risk of oral cancer. Reactive oxygen species formed from polyphenolic betel quid ingredients and lime at alkaline pH have been implicated as the agents responsible for DNA and tissue damage. To determine whether hydroxyl radical (HO.

Formation of 1,N6-ethenoadenine and 3,N4-ethenocytosine by lipid peroxidation products and nucleic acid bases.

Lipid peroxidation (LPO) products are known to interact with DNA, yielding several types of adduct with nucleobases. In this study, we demonstrate the formation of two ethenobase adducts, 1,N6-ethenoadenine and 3,N4-ethenocytosine, by reaction of LPO products with nucleic acid bases. Rat liver microsomes were incubated at 37 degrees C for 30 min in the presence of inducers of LPO [Fe(II) or cumene hydroperoxide] and adenine or cytosine nucleotides or nucleosides, followed by further heating at 80 degrees C for 30 min to complete the reactions.

1,N6-ethenodeoxyadenosine and 3,N4-ethenodeoxycytine in liver DNA from humans and untreated rodents detected by immunoaffinity/32P-postlabeling.

The etheno-bridged exocyclic DNA adducts 1,N6-ethenodeoxyadenosine (epsilon dA) and 3,N4-ethenodeoxycytine (epsilon dC) can be formed by several structurally diverse carcinogens and mutagens that include vinyl chloride and urethane. In order to investigate the occurrence and persistence of these adducts in rodents exposed to such DNA-damaging agents, an ultra-sensitive detection method has been developed. It is based on immunoaffinity purification of the etheno adducts and subsequent 32P-postlabelling followed by separation as 5'-monophosphates on polyethyleneimine-cellulose-coated thin-layer plates.

Metabolism of N'-nitrosonornicotine by adult and fetal human oesophagal cultures.

The metabolism of [3H]labelled N-Nitrosonornicotine a major constituent of the class of Tobacco Specific Nitrosamines was studied in adult and fetal human oesophageal cultures. The metabolites were separated by HPLC and were identified when compared to the standards as OH-acid from 5'hydroxylation, NNN-1-N-oxide formed via the pyridine N-oxidation pathway and Keto acid from 2'hydroxylation in both the adult and fetal cultures. These results indicate that hydroxylation which leads to electrophilic diazohyroxides is the major pathway of NNN metabolism in cultured human oesophagus.

Endogenous formation of N-nitrosoproline and other N-nitrosamino acids in tobacco users.

The endogenous formation of N-nitroso compounds in tobacco users, namely chewers of tobacco + lime, betel quid with tobacco, and without tobacco, was determined by N-nitrosoproline test. Twenty-four- or six-hour urine samples were collected from volunteers for 3 days: day 1 without proline, day 2 after ingesting 100 mg proline three times a day and day 3 after ingesting 100 mg proline together with 100 mg ascorbic acid three times a day. The urine samples were analysed for the following N-nitrosamino acids: N-nitrosoproline, N-nitrososarcosine, N-nitrosopropionic acid, N-nitrosobutyric acid, N-nitrosothiozolidine-4-carboxylic acid, and N-methyl nitrosothiozolidine-4-carboxylic acid using gas chromatography-thermal energy analyser.