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Molecules (Basel, Switzerland) Nov 2020A GC-MS/MS method with EI ionization was developed and validated to detect and quantify -nitrosodimethylamine (NDMA) and seven other nitrosamines in 105 samples of...
A GC-MS/MS method with EI ionization was developed and validated to detect and quantify -nitrosodimethylamine (NDMA) and seven other nitrosamines in 105 samples of metformin tablets from 13 different manufactures. Good linearity for each compound was demonstrated over the calibration range of 0.5-9.5 ng/mL. The assay for all substances was accurate and precise. NDMA was not detected in the acquired active pharmaceutical ingredient (API); however, NDMA was detected in 64 (85.3%) and 22 (91.7%) of the finished product and prolonged finished product samples, respectively. European Medicines Agency recommends the maximum allowed limit of 0.032 ppm in the metformin products. Hence, 28 finished products and 7 pronged dosage products were found to exceed the acceptable limit of daily intake of NDMA contamination. The implications of our findings for the testing of pharmaceutical products are discussed.
Topics: Artifacts; Calibration; Dimethylnitrosamine; Drug Contamination; Drug Design; Europe; Gas Chromatography-Mass Spectrometry; Limit of Detection; Linear Models; Metformin; Pharmaceutical Preparations; Powders; Solvents; Tablets; Tandem Mass Spectrometry; Temperature
PubMed: 33202951
DOI: 10.3390/molecules25225304 -
British Journal of Experimental... Apr 1977A Porton and a hooded rat strain showed a raised LD50 for dimethylnitrosamine (DMN) when pre-conditioned on a protein-free and/or a sugar diet. Little or no such...
The effect of a protein-free diet, a sugar diet and of carbon tetrachloride administration on the toxicity and rate of metabolism of dimethylnitrosamine in different rat strains.
A Porton and a hooded rat strain showed a raised LD50 for dimethylnitrosamine (DMN) when pre-conditioned on a protein-free and/or a sugar diet. Little or no such differential toxicity between normal and diet-fed animals was found for rats of the Wistar, BDIX and CFY strains. Pre-treatment with CCl4 did not alter significantly the toxicity of DMN in the Wistar strain. All 5 rat strains treated by diet or CCl4 administration metabolized DMN at a very much slower rate than did the controls, the rates for the different strains being quantitatively similar. It is concluded that the toxicity of DMN is not necessarily related to its rate of metabolism and that the effect of diet or CCl4 treatment of DMN toxicity is dependent on the strain of rat used.
Topics: Animals; Carbon Tetrachloride; Dietary Carbohydrates; Dimethylnitrosamine; Nitrosamines; Protein Deficiency; Rats; Rats, Inbred Strains
PubMed: 861170
DOI: No ID Found -
Genes and Environment : the Official... 2016Toxicogenomics is a rapidly developing discipline focused on the elucidation of the molecular and cellular effects of chemicals on biological systems. As a collaborative... (Review)
Review
Toxicogenomics is a rapidly developing discipline focused on the elucidation of the molecular and cellular effects of chemicals on biological systems. As a collaborative study group of Toxicogenomics/JEMS·MMS, we conducted studies on hepatocarcinogens in rodent liver in which 100 candidate marker genes were selected to discriminate genotoxic hepatocarcinogens from non-genotoxic hepatocarcinogens. Differential gene expression induced by 13 chemicals were examined using DNA microarray and quantitative real-time PCR (qPCR), including eight genotoxic hepatocarcinogens [o-aminoazotoluene, chrysene, dibenzo[a,l]pyrene, diethylnitrosamine (DEN), 7,12-dimethylbenz[a]anthracene, dimethylnitrosamine, dipropylnitrosamine and ethylnitrosourea (ENU)], four non-genotoxic hepatocarcinogens [carbon tetrachloride, di(2-ethylhexyl)phthalate (DEHP), phenobarbital and trichloroethylene] and a non-genotoxic non-hepatocarcinogen [ethanol]. Using qPCR, 30 key genes were extracted from mouse livers at 4 h and 28 days following dose-dependent gene expression alteration induced by DEN and ENU: the most significant changes in gene expression were observed at 4 h. Next, we selected key point times at 4 and 48 h from changes in time-dependent gene expression during the acute phase following administration of chrysene by qPCR. We successfully showed discrimination of eight genotoxic hepatocarcinogens [2-acetylaminofluorene, 2,4-diaminotoluene, diisopropanolnitrosamine, 4-dimethylaminoazobenzene, 4-(methylnitsosamino)-1-(3-pyridyl)-1-butanone, N-nitrosomorpholine, quinoline and urethane] from four non-genotoxic hepatocarcinogens [1,4-dichlorobenzene, dichlorodiphenyltrichloroethane, DEHP and furan] using qPCR and principal component analysis. Additionally, we successfully identified two rat genotoxic hepatocarcinogens [DEN and 2,6-dinitrotoluene] from a nongenotoxic-hepatocarcinogen [DEHP] and a non-genotoxic non-hepatocarcinogen [phenacetin] at 4 and 48 h. The subsequent gene pathway analysis by Ingenuity Pathway Analysis extracted the DNA damage response, resulting from the signal transduction of a p53-class mediator leading to the induction of apoptosis. The present review of these studies suggests that application of principal component analysis on the gene expression profile in rodent liver during the acute phase is useful to predict genotoxic hepatocarcinogens in comparison to non-genotoxic hepatocarcinogens and/or non-carcinogenic hepatotoxins.
PubMed: 27482301
DOI: 10.1186/s41021-016-0041-0 -
Journal of Hazardous Materials May 2023N-nitrosamines are formed during different industrial processes and are of significant concern due to their carcinogenic and mutagenic properties. This study reports...
N-nitrosamines are formed during different industrial processes and are of significant concern due to their carcinogenic and mutagenic properties. This study reports concentrations of N-nitrosamines in eight different industrial wastewater treatment plants in Switzerland and the variability of their abundance. Only four N-nitrosamines species, N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodibutylamine (NDPA) and N-nitrosomorpholine (NMOR) were above the limit of quantification in this campaign. Remarkably high concentrations (i.e. up to 975 μg NDMA/L, 90.7 μg NDEA/L, 1.6 μg NDPA/L and 710 μg NMOR/L) of these N-nitrosamines were detected at seven of eight sites. These concentrations are two to five orders of magnitude higher than those typically detected in municipal wastewater effluents. These results suggest that industrial effluents may be a major source of N-nitrosamines. Although very high concentrations of N-nitrosamine have been detected in industrial discharges, various processes in surface water can partially mitigate their concentrations (e.g. photolysis, biodegradation and volatilization) and hence the risk to human health and aquatic ecosystems. Nevertheless, there is little information on long-term effects on aquatic organisms and therefore the discharge of N-nitrosamines to the environment should be avoided until the impact on ecosystems is assessed. During winter a less efficient mitigation of N-nitrosamines can be expected (lower biological activity, less sunlight) and therefore, emphasis should be put on this season in future risk assessment studies.
Topics: Humans; Switzerland; Ecosystem; Nitrosamines; Dimethylnitrosamine; Diethylnitrosamine
PubMed: 36867906
DOI: 10.1016/j.jhazmat.2023.131094 -
Archives of Toxicology Jun 2024Dietary exposure to N-nitrosamines has recently been assessed by the European Food Safety Authority (EFSA) to result in margins of exposure that are conceived to...
Dietary exposure to N-nitrosamines has recently been assessed by the European Food Safety Authority (EFSA) to result in margins of exposure that are conceived to indicate concern with respect to human health risk. However, evidence from more than half a century of international research shows that N-nitroso compounds (NOC) can also be formed endogenously. In this commentary of the Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG), the complex metabolic and physiological biokinetics network of nitrate, nitrite and reactive nitrogen species is discussed with emphasis on its influence on endogenous NOC formation. Pioneering approaches to monitor endogenous NOC have been based on steady-state levels of N-nitrosodimethylamine (NDMA) in human blood and on DNA adduct levels in blood cells. Further NOC have not been considered yet to a comparable extent, although their generation from endogenous or exogenous precursors is to be expected. The evidence available to date indicates that endogenous NDMA exposure could exceed dietary exposure by about 2-3 orders of magnitude. These findings require consolidation by refined toxicokinetics and DNA adduct monitoring data to achieve a credible and comprehensive human health risk assessment.
Topics: Humans; Risk Assessment; Nitrosamines; Dietary Exposure; Dimethylnitrosamine; DNA Adducts; Food Contamination; Food Safety; Animals; Nitrites; Nitrates; Reactive Nitrogen Species
PubMed: 38573336
DOI: 10.1007/s00204-024-03726-1 -
BMC Gastroenterology Nov 2015Liver sinusoidal endothelial cells (SECs), hepatic stellate cells (HSCs) and Kupffer cells (KCs) are involved in the development of liver fibrosis and represent a...
BACKGROUND/AIMS
Liver sinusoidal endothelial cells (SECs), hepatic stellate cells (HSCs) and Kupffer cells (KCs) are involved in the development of liver fibrosis and represent a potential therapeutic target. The therapeutic effects on liver fibrosis of sorafenib, a multiple tyrosine kinase inhibitor, and gadolinium chloride (GdCl3), which depletes KCs, were evaluated in rats.
METHODS
Liver fibrosis was induced in rats with dimethylnitrosamine, and the effects of sorafenib and/or GdCl3 in these rats were monitored. Interactions among ECs, HSCs and KCs were assessed by laser confocal microscopy.
RESULTS
The combination of sorafenib and GdCl3, but not each agent alone, attenuated liver fibrosis and significantly reduced liver function and hydroxyproline (Hyp). Sorafenib significantly inhibited the expression of angiogenesis-associated cell markers and cytokines, including CD31, von Willebrand factor (vWF), and vascular endothelial growth factor, whereas GdCl3 suppressed macrophage-related cell markers and cytokines, including CD68, tumor necrosis factor-α, interleukin-1β, and CCL2. Laser confocal microscopy showed that sorafenib inhibited vWF expression and GdCl3 reduced CD68 staining. Sorafenib plus GdCl3 suppressed the interactions of HSCs, ECs and KCs.
CONCLUSION
Sorafenib plus GdCl3 can suppress collagen accumulation, suggesting that this combination may be a potential therapeutic strategy in the treatment of liver fibrosis.
Topics: Angiogenic Proteins; Animals; Anti-Inflammatory Agents; Cytokines; Dimethylnitrosamine; Drug Therapy, Combination; Gadolinium; Hepatic Stellate Cells; Hepatocytes; Hydroxyproline; Kupffer Cells; Liver; Liver Cirrhosis; Niacinamide; Phenylurea Compounds; Protein Kinase Inhibitors; Rats; Rats, Wistar; Sorafenib
PubMed: 26572488
DOI: 10.1186/s12876-015-0380-5 -
Environmental Health Perspectives Mar 1993Investigation of urinary markers as indices of endogenous nitrosation and of gastric cancer etiology has been a major focus of our work. As part of this effort, studies... (Review)
Review
Investigation of urinary markers as indices of endogenous nitrosation and of gastric cancer etiology has been a major focus of our work. As part of this effort, studies have been carried out on a Colombian population at high risk for gastric cancer. In this group, nitrosoproline excretion was highly correlated with nitrate excretion in the subpopulation with advanced gastric pathology, but not in control subpopulations with more normal stomachs. Neither urinary 7-methylguanine nor 3-methyladenine was strongly related to gastric pathology or to urinary nitrate or nitrosoproline levels. More recently, as evidence has accumulated concerning the importance of nitric oxide as a cellular messenger, we have begun research toward developing markers for the presence of nitric oxide and for endogenous nitrosation via this compound. Nitric oxide is formed from arginine by activated endothelial cells as a messenger for vasodilation. We have shown that prolonged exercise leads to increased urinary nitrate and that when 15N-arginine is ingested by humans, 15N-nitrate levels increase in 24-hr urine collections. Nitrosohydroxyethylglycine and 3-nitrotyrosine were evaluated as indices for the formation of N-nitrosomorpholine and for the nitration of protein, respectively, under experimental conditions (e.g., immunostimulation) expected to enhance nitric oxide formation. Nitrotyrosine has not proved useful as a biomarker for nitration/nitrosation reactions in immunostimulated rats. Immunostimulation of rats following administration of morpholine led to increases in urinary nitrate and nitrosohydroxyethylglycine. This procedure, however, would not be appropriate for humans due to the toxicity of morpholine and the carcinogenicity of N-nitrosomorpholine.
Topics: Adenine; Alkylating Agents; Animals; Biomarkers; DNA Damage; Dimethylnitrosamine; Humans; Nitric Oxide; Nitrosamines; Nitroso Compounds; Risk Factors; Stomach Neoplasms; Tyrosine
PubMed: 8319614
DOI: 10.1289/ehp.9399155 -
World Journal of Gastroenterology Feb 2001To evaluate the antifibrotic effect of different doses of recombinant human Gamma-Interferon (IFN-gamma) in two rat models of hepatic fibrosis, and to observe its effect... (Clinical Trial)
Clinical Trial
AIM
To evaluate the antifibrotic effect of different doses of recombinant human Gamma-Interferon (IFN-gamma) in two rat models of hepatic fibrosis, and to observe its effect on moderate chronic hepatitis B virus fibrosis.
METHODS
Hepatic fibrosis was successfully induced in 150 and 196 rats by subcutaneous injection of carbon tetrachloride (CCl4) and intraperitoneal injection of dimethylnitrosamine (DMN), respectively. Each of the two model groups was divided into: (1) fibrotic model group; (2) colchicine treatment group (0.1 mg/kg/day, gastrogavage for 8 weeks); (3) high-dose IFN-gamma group (15 MU/kg per day, i.m. for 8 weeks); (4) medium-dose IFN-gamma group (5 MU/kg daily, i.m. for 8 weeks); and (5) Y low-dose IFN-gamma group (1.67 MU/kg daily, i.m. for 8 weeks). Another group of 10 rats without any treatment was used as normal controls. At the end of the experiment, semi-quantitative histopathological scores of inflammation and fibrosis, liver alpha smooth muscle actin (alpha-SMA) expression level, liver hydroxyl proline content and serum hyaluronic acid levels were compared. And 47 medium chronic hepatitis B viral fibrosis patients were studied. They were given IFN-gamma treatment, 100 MU/day i.m. for the first three months and 100 MU qod i.m. for the next six months. Semi-quantitative pathological scores of inflammation and fibrosis and serum hepatic fibrosis indices were compared within the 9 months.
RESULTS
In animal experiment, the pathological fibrosis scores and liver hydroxyl proline content were found to be significantly lower in rats treated with different doses of IFN-gamma as compared with rats in fibrotic model group induced by either CCl4 or DMN, in a dose-dependent manner. For CCl4-induced model, pathological fibrosis scores in high, medium and low doses IFN-gamma groups were 5.10 +/- 2.88, 7.70 +/- 3.53 and 8.00 +/- 3.30, respectively, but the score was 14.60 +/- 7.82 in fibrotic model group. Hydroxyl proline contents were 2.83 +/- 1.18, 3.59 +/- 1.22 and 4.80 +/- 1.62, in the three IFN-gamma groups, and 10.01 +/- 3.23 in fibrotic model group. The difference was statistically significant (P<0.01). Similar results were found in DMN-induced model. Pathological fibrosis scores were 6.30 +/- 0.48, 8.10 +/- 2.72 and 8.30 +/- 2.58, in high, medium and low doses IFN-gamma groups, and 12.60 +/- 3.57 in fibrotic model group. Hydroxyl proline contents were 2.72 +/- 0.58, 3.14 +/- 0.71 and 3.62 +/- 1.02, in the three IFN-gamma groups, and 12.79 +/- 1.54 in fibrotic model group. The difference was statistically significant (P<0.01). Serum hepatic fibrosis indices decreased significantly in the 47 patients after IFN-gamma treatment (HA: 433.38 +/- 373.00 vs 281.57 +/- 220.48; LN: 161.22 +/- 41.02 vs 146 +/- 35 +/- 44. 67; PC III: 192.59 +/- 89.95 vs 156.98 +/- 49.22; C-I: 156.30 +/- 44.01 vs 139.14 +/- 34.47) and the differences between the four indices were significant (P <0.05). Thirty-three patients received two liver biopsies, one before and one after IFN-gamma treatment. In thirty of 33 patients IFN-gamma had better effects according to semi-quantitative pathological scores (8.40 +/- 5.83 vs 5.30 +/- 4.05, P<0.05).
CONCLUSION
All the three doses of IFN-gamma are effective in treating rat liver fibrosis induced by either CCl4 or DMN, the higher the dose, the better the effect. And IFN-gamma is effective for patients with moderate chronic hepatitis B viral fibrosis.
Topics: Animals; Antineoplastic Agents; Biopsy; Carbon Tetrachloride; Dimethylnitrosamine; Disease Models, Animal; Female; Hepatitis B, Chronic; Humans; Hyaluronic Acid; Hydroxyproline; Interferon-gamma; Liver; Liver Cirrhosis; Liver Function Tests; Male; Rats; Rats, Sprague-Dawley; Recombinant Proteins
PubMed: 11819731
DOI: 10.3748/wjg.v7.i1.42 -
Biomedicine & Pharmacotherapy =... Jul 2022Osteopontin (OPN) is a matricellular cytokine and a stress-induced profibrogenic molecule that promotes activation of stellate cells during the pathogenesis of hepatic...
Osteopontin (OPN) is a matricellular cytokine and a stress-induced profibrogenic molecule that promotes activation of stellate cells during the pathogenesis of hepatic fibrosis. We studied the protective effects of epigallocatechin-3-gallate (EGCG) to suppress oxidative stress, inhibit OPN expression, and prevent experimentally induced hepatic fibrosis. Liver injury was induced with intraperitoneal injections of N-nitrosodimethylamine (NDMA) in a dose of 1 mg/100 g body weight on 3 consecutive days of a week for 28 days. A group of rats received 0.2 mg EGCG/100 g body weight orally everyday during the study. The animals were sacrificed on day 28th from the beginning of exposure. Serum levels of AST, ALT, OPN, malondialdehyde, collagen type IV, and hyaluronic acid were measured. Immunohistochemistry and/or real-time PCR were performed for α-SMA, 4-HNE, OPN, collagen type I, and type III. Serial administrations of NDMA produced well developed fibrosis and early cirrhosis in rat liver. Treatment with EGCG significantly reduced serum/plasma levels of AST, ALT, OPN, malondialdehyde, collagen type IV, and hyaluronic acid and prevented deposition of collagen fibers in the hepatic tissue. Protein and/or mRNA levels demonstrated marked decrease in the expression of α-SMA, 4-HNE, OPN, collagen type I, and type III. Treatment with EGCG prevented excessive generation of reactive oxygen species, suppressed oxidative stress, significantly reduced serum and hepatic OPN levels, and markedly attenuated hepatic fibrosis. The results indicated that EGCG could be used as a potent therapeutic agent to prevent hepatic fibrogenesis and related adverse events.
Topics: Animals; Body Weight; Catechin; Collagen Type I; Collagen Type IV; Dimethylnitrosamine; Fibrosis; Hepatic Stellate Cells; Hyaluronic Acid; Liver; Liver Cirrhosis; Malondialdehyde; Osteopontin; Rats
PubMed: 35594711
DOI: 10.1016/j.biopha.2022.113111 -
Proceedings of the Royal Society of... Oct 1975
Topics: Animals; Diethylstilbestrol; Dimethylnitrosamine; Female; Fetal Diseases; Humans; Infant, Newborn; Maternal-Fetal Exchange; Neoplasms; Neoplasms, Radiation-Induced; Placenta; Pregnancy; Radiography; Rats; Vaginal Neoplasms
PubMed: 1208519
DOI: No ID Found