Search results for "Nitrosamine"
showing 10 items of 32 documents
N-Methyl-4-(4-nitrophenyl)-N-nitroso-1,3-thiazol-2-amine
2017
The title compound, C10H8N4O3S, is almost planar [dihedral angle between the rings = 2.2 (2)°; r.m.s. deviation for the non-H atoms = 0.050 Å]. In the crystal, C—H...O and C—H...N hydrogen bonds link the molecules into (10-2) layers.
Effect of antibodies against cytochrome P-450 on demethylation and denitrosation of N-nitrosodimethylamine and N-nitrosomethylaniline.
1988
Rat liver microsomes which were induced either with ethanol or PB were incubated with NDMA or NMA. Formaldehyde generation and nitrite formation were measured as metabolic parameters for oxidative bioactivation and denitrosation, respectively. The influence of antiserum PB3a1 and PB22 containing antibodies against the corresponding cytochrome P-450 species on both metabolic functions was investigated. The results showed that the influence on formaldehyde production and denitrosation varied independently in that both parameters were either not affected, or influenced in an opposite way, or inhibited to a different degree. Especially remarkable was the 80% inhibition of formaldehyde generatio…
Hypothesis: Etiologic and Molecular Mechanistic Leads for Sporadic Neurodegenerative Diseases Based on Experience With Western Pacific ALS/PDC
2019
Seventy years of research on Western Pacific amyotrophic lateral sclerosis and Parkinsonism-dementia Complex (ALS/PDC) have provided invaluable data on the etiology, molecular pathogenesis and latency of this disappearing, largely environmental neurodegenerative disease. ALS/PDC is linked to genotoxic chemicals (notably methylazoxymethanol, MAM) derived from seed of the cycad plant (Cycas spp.) that were used as a traditional food and/or medicine in all three disease-affected Western Pacific populations. MAM, nitrosamines and hydrazines generate methyl free radicals that damage DNA (in the form of O6-methylguanine lesions) that can induce mutations in cycling cells and degenerative changes …
Use of HepG2 cell line for direct or indirect mutagens screening: comparative investigation between comet and micronucleus assays.
2003
International audience; In the present study, DNA-damage and clastogenic or aneugenic effects of genotoxic compounds were examined in a metabolically competent human cell line (HepG2 cells) using the micronucleus and the comet assays. Compounds with various action mechanisms were tested: direct mutagens such as 4-nitroquinoline-N-oxide (4-NQO) and methyl methanesulfonate (MMS) and indirect mutagens requiring biotransformation to be active such as N-nitrosodimethylamine (NDMA), benzo[a]pyrene (B[a]P) and 2-acetylaminofluorene (2-AAF). The compounds were first tested for cytotoxicity by measuring their effects on RNA synthesis inhibition in HepG2 cells. 4-NQO, B[a]P and 2-AAF were the most po…
Kinase-independent functions of RIPK1 regulate hepatocyte survival and liver carcinogenesis.
2017
The mechanisms that regulate cell death and inflammation play an important role in liver disease and cancer. Receptor-interacting protein kinase 1 (RIPK1) induces apoptosis and necroptosis via kinase-dependent mechanisms and exhibits kinase-independent prosurvival and proinflammatory functions. Here, we have used genetic mouse models to study the role of RIPK1 in liver homeostasis, injury, and cancer. While ablating either RIPK1 or RelA in liver parenchymal cells (LPCs) did not cause spontaneous liver pathology, mice with combined deficiency of RIPK1 and RelA in LPCs showed increased hepatocyte apoptosis and developed spontaneous chronic liver disease and cancer that were independent of TNF…
Determination of N-nitrosodiethanolamine in cosmetic products by reversed-phase dispersive liquid-liquid microextraction followed by liquid chromatog…
2016
A new analytical method for the determination of N-nitrosodiethanolamine (NDELA), a very harmful compound not allowed in cosmetic products, is presented. The method is based on a new approach of dispersive liquid-liquid microextraction (DLLME) useful for extraction of highly polar compounds, called reversed-phase DLLME (RP-DLLME), followed by liquid chromatography-ultraviolet/visible (LC-UV/Vis) determination. The variables involved in the RP-DLLME process were studied to provide the best enrichment factors. Under the optimized conditions, a mixture of 750µL of acetone (disperser solvent) and 125µL of water (extraction solvent) was rapidly injected into 5mL of toluene sample solution. The e…
Determination of N -nitrosamines in cosmetic products by vortex-assisted reversed-phase dispersive liquid-liquid microextraction and liquid chromatog…
2018
A new analytical method for the simultaneous determination of trace levels of seven prohibited N-nitrosamines (N-nitrosodimethylamine, N-nitrosoethylmethylamine, N-nitrosopyrrolidine, N-nitrosodiethylamine, N-nitrosopiperidine, N-nitrosomorpholine, and N-nitrosodiethanolamine) in cosmetic products has been developed. The method is based on vortex-assisted reversed-phase dispersive liquid-liquid microextraction, which allows the extraction of highly polar compounds, followed by liquid chromatography with mass spectrometry. The variables involved in the extraction process were studied to obtain the highest enrichment factor. Under the selected conditions, 75 μL of water as extraction solvent …
Polychlorinated biphenyls, classified as either phenobarbital- or 3-methylcholanthrene-type inducers of cytochrome P-450, are both hepatic tumor prom…
1986
Abstract The cytochrome P -450 isozymes, cytochrome P -450 MC 1 and MC 2 , purified from rats treated with 3-methylcholanthrene (MC), were found by immunohistochemical staining to be strongly induced in the livers of rats treated with 3,3′, 4,4′-tetrachlorobiphenyl (TCBP), while the cytochrome P -450 isozymes, PB 1 and PB 2 , purified from the livers of rats treated with phenobarbital (PB), were shown to be induced in the livers of rats treated with 2,2′, 4,4′, 5,5′-hexachlorobiphenyl (HCBP). The latter compound also strongly induced NADPH-cytochrome P -450-reductase. Following induction, all 5 enzymes were located preferentially in the centrilobular and midzonal region of the liver acinus.…
Liver subcellular fractions from rats treated by organosulfur compounds from Allium modulate mutagen activation
2000
The effects of in vivo administration of naturally occurring organosulfur compounds (OSCs) from Allium species were studied on the activation of several mutagens. Male SPF Wistar rats were given p.o. one of either diallyl sulfide (DAS), diallyl disulfide (DADS), dipropyl sulfide (DPS) or dipropyl disulfide (DPDS) during 4 consecutive days and the ability of hepatic S9 and microsomes from treated rats to activate benzo[a]pyrene (BaP), cyclophosphamide (CP), dimethylnitrosamine (DMN), N-nitrosopiperidine (N-PiP) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was determined in the Ames test. Administration of DAS, DPS and DPDS resulted in a significant increase of the activation of…
Cytogenetic effects of promutagens in genetically engineered V79 Chinese hamster cells expressing cytochromes P450.
1993
Abstract V79 Chinese hamster cell lines genetically engineered to express rat CYP2B1, CYP1A1, CYP1A2, and their parental cell lines V79-MZ, without acetyltransferase, and V79-NH, with acetyltransferase, were studied for chromosome aberrations and sister chromatid exchange induced by aflatoxin B 1 , cyclophosphamide, benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene and dimethylnitrosamine. The parental V79 cell lines did not show clastogenic effects. Significant clastogenic effects were observed after an 18 h exposure to aflatoxin B 1 and cyclophosphamide in CYP2B1 expressing cells, to benzo[a]pyrene in CYP1A1 and CYP1A2 expressing cells, to 7,12-dimethylbenz[a]anthracene and dimethylnitrosami…