Showing papers on "Sodium dichromate published in 2001"
TL;DR: Taking together, oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptotic regulatory gene p53 are involved in chromium (VI)‐induced toxicity and carcinogenesis.
Abstract: Chromium (VI) is a widely used industrial chemical, extensively used in paints, metal finishes, steel including stainless steel manufacturing, alloy cast irons, chrome, and wood treatment. On the contrary, chromium (III) salts such as chromium polynicotinate, chromium chloride and chromium picolinate, are used as micronutrients and nutritional supplements, and have been demonstrated to exhibit a significant number of health benefits in rodents and humans. However, the cause for the hexavalent chromium to induce cytotoxicity is not entirely understood. A series of in vitro and in vivo studies have demonstrated that chromium (VI) induces an oxidative stress through enhanced production of reactive oxygen species (ROS) leading to genomic DNA damage and oxidative deterioration of lipids and proteins. A cascade of cellular events occur following chromium (VI)‐induced oxidative stress including enhanced production of superoxide anion and hydroxyl radicals, increased lipid peroxidation and genomic DNA fragmentation, modulation of intracellular oxidized states, activation of protein kinase C, apoptotic cell death and altered gene expression. In this paper, we have demonstrated concentration‐ and time‐dependent effects of sodium dichromate (chromium (VI) or Cr (VI)) on enhanced production of superoxide anion and hydroxyl radicals, changes in intracellular oxidized states as determined by laser scanning confocal microscopy, DNA fragmentation and apoptotic cell death (by flow cytometry) in human peripheral blood mononuclear cells. These results were compared with the concentration-dependent effects of chromium (VI) on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Chromium (VI)‐induced enhanced production of ROS, as well as oxidative tissue and DNA damage were observed in these cells. More pronounced effect was observed on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Furthermore, we have assessed the effect of a single oral LD50 dose of chromium (VI) on female C57BL/6Ntac and p53‐deficient C57BL/6TSG p53 mice on enhanced production of superoxide anion, lipid peroxidation and DNA fragmentation in the hepatic and brain tissues. Chromium (VI)‐induced more pronounced oxidative damage in p53 deficient mice. This in vivo study highlighted that apoptotic regulatory protein p53 may play a major role in chromium (VI)‐induced oxidative stress and toxicity. Taken together, oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptotic regulatory gene p53 are involved in chromium (VI)‐induced toxicity and carcinogenesis.
224 citations
TL;DR: In this paper, the photoreduction of hydrated sodium dichromate in the presence of carbon compounds has been studied by X-ray photoelectron spectroscopy (XPS) and it has been shown that the photochemical and thermal reduction appears to be prevented by cooling with liquid nitrogen and using hydrocarbon-free vacuum pumping conditions.
54 citations
TL;DR: Investigation of the ability of sodium dichromate to cause DNA strand breaks in three populations of cells, human whole blood cells, isolated human peripheral blood lymphocytes and cultured A549 lung epithelial cells, found a role for DNA base oxidation in the mechanism of dichromates-induced DNA strand break formation.
Abstract: Hexavalent chromium [Cr(VI)] is a genotoxic carcinogen for which inhalation is a major potential route of exposure in occupational settings. In the present study, the ability of sodium dichromate to cause DNA strand breaks in three populations of cells, human whole blood cells, isolated human peripheral blood lymphocytes and cultured A549 lung epithelial cells, was investigated. Treatment with non-cytotoxic concentrations of sodium dichromate (for 1 h) resulted in a concentration-dependent increase in the number of DNA strand breaks as measured by the Comet assay. The lowest concentrations of sodium dichromate that resulted in a statistically significant (P < 0.01) increase in the number of DNA strand breaks were 500, 50 and 10 microM, respectively, in these cells. The use of formamidopyrimidine glycosylase increased the sensitivity of detection of strand breaks in A549 cells 10-fold, suggesting a role for DNA base oxidation in the mechanism of dichromate-induced DNA strand breaks. In support of this hypothesis, immunocytochemistry indicated an elevation of 8-oxodeoxyguanosine in A549 cells treated with 10 and 500 microM sodium dichromate for 1 h. We also demonstrated 2.11- and 2.5-fold ranges in the level of control and dichromate (500 microM)-induced DNA strand breaks, respectively, in cells of whole blood within a group of healthy volunteers (n = 26). A statistically significant (P < 0.001) positive Pearson's correlation (r = 0.606) was found between control and treated levels of DNA strand breaks, suggesting that factors responsible for relatively low levels of DNA strand breaks in untreated PBL may also offer protection against the formation of dichromate-induced DNA strand breaks.
53 citations
TL;DR: Aqueous polymerization of 3-chloroaniline (mCA) was studied using sodium dichromate as oxidant in the presence of hydrochloric acid in this article.
Abstract: Aqueous polymerization of 3-chloroaniline (mCA) was studied using sodium dichromate as oxidant in the presence of hydrochloric acid The effect of hydrochloric acid, sodium dichromate and monomer concentration on the polymerization rate, specific viscosity of the obtained polymer and ac conductivity was investigated The initial and overall reaction rates increase with increasing hydrochloric acid concentration or sodium dichromate concentration, but decrease with increasing monomer concentration The specific viscosity values (η sp ) increase with increasing hydrochloric acid concentration or monomer concentration, which means that the molecular weight of the polymer samples increases accordingly On the contrary, the molecular weight decreases with increasing sodium dichromate concentration The highest ac conductivity value of the obtained polymer was found for 00255 moll -1 of Na 2 Cr 2 O 7 , 08 moll -1 HCl and 00956 moll -1 monomer concentration in the reaction medium The order of the polymerization reaction with respect to hydrochloric acid, Na 2 Cr 2 O 7 and monomer concentration was found to be 10, 09 and 075, respectively The apparent activation energy (E a ) for this polymerization system was found to be 13674 x 10 4 mol -1 The obtained poly(3-chloroaniline) was characterized by UV-visible, IR and 1 H NMR spectroscopy X-ray diffraction analysis and electron microscopy studies were carried out Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) results were used to confirm the structure
37 citations
TL;DR: A model, which provides repetitive incubations in human upper aerodigestive tract mucosa cultures, may help to assess genotoxic hazards posed by environmental pollutants that have a cumulative character in repetitive or chronic exposure in vivo.
29 citations
TL;DR: In this paper, the aqueous polymerization of m-methylaniline (mMA) was studied using sodium dichromate as oxidant in the presence of hydrochloric acid.
Abstract: The aqueous polymerization of m-methylaniline (mMA) was studied using sodium dichromate as oxidant in the presence of hydrochloric acid. The effect of hydrochloric acid, sodium dichromate and monomer concentration on the polymerization rate, specific viscosity of the obtained polymer and a.c.conductivity was investigated. The initial and overall reaction rates increase with the increase of hydrochloric acid concentration or sodium dichromate concentration but decrease with the increase of the monomer concentration. The specific viscosity values increase with increasing of hydrochloric acid concentration or monomer concentration, which means that the molecular weight of the polymer samples increases in the same direction. But the molecular weight decreases with the increase of sodium dichromate concentration. The highest a.c.conductivity value of the obtained polymer was found in case of using 0.023304 g mol/L of Na2Cr2O7 0.2 M HCI and 0.093225 M monomer solution in the reaction medium. The order ...
28 citations
TL;DR: The investigation of renal amino acid handling confirms that both CP and chromate are nephrotoxins, that CP was more neph rotoxic in 55-day-old animals compared to immature rats as could be demonstrated before using other parameters for nephRotoxicity testing and showed that determination of renal Amin acid handling is a highly sensitive marker for nePhrotoxicity testing, especially in immature rats.
Abstract: The effects of sodium dichromate (chromate; 1 mg/100 g b. wt. s.c.) and cisdiamminedichloroplatinum(II) (CP; 0.6 mg/100 g b. wt. i. p.) on renal amino acid excretion and plasma amino acid composition were investigated in 10- and 55-day-old anaesthetised rats. On the basis of diuresis experiments on conscious rats the mentioned doses and times (1st day after chromate in both age groups and in 10-day-old rats after CP and 3rd day after CP in adult rats) were found out to be optimal for the characterisation of amino acid transport after heavy metal poisoning. Interestingly, in conscious 10-day-old rats chromate nephrotoxicity is not detectable after 1 mg/100 g b. wt. whereas all of the other experimental groups showed nephrotoxic effects of chromate and CP in conscious rats. Urine volumes are lower, but not significantly, in anaesthetised immature rats, independently of the administered nephrotoxin. But GFR is significantly lower in 10-day-old rats, both in controls and after CP, whereas after chromate GFR is significantly reduced only in adult rats and age differences disappeared. In principle the renal fractional excretion (FE) of amino acids was distinctly higher in immature rats as a sign of lower amino acid reabsorption capacity. Nevertheless, the amino acid plasma concentrations were relatively high in immature rats. However, both chromate and CP did not distinctly influence amino acid plasma concentrations. But in both age groups the administration of chromate and CP significantly decreased amino acid reabsorption capacity (increase in FE) as a sign of nephrotoxicity, most pronounced in adult rats after CP. The investigation of renal amino acid handling confirms (1) that both CP and chromate are nephrotoxins, (2) that CP was more nephrotoxic in 55-day-old animals compared to immature rats as could be demonstrated before using other parameters for nephrotoxicity testing and showed (3) that determination of renal amino acid handling is a highly sensitive marker for nephrotoxicity testing, especially in immature rats.
12 citations
TL;DR: Mutagen sensitivity of NPC patients was shown to be elevated for a selected xenobiotic, whereas a general elevation of DNA fragility was not present, and further studies on mutagen sensitivity as an endogenous risk factor influencing the susceptibility of patients at the time of first diagnosis of nasopharyngeal carcinomas are warranted.
Abstract: Primary nasopharyngeal carcinomas (NPCs) may be of various types, including squamous cell carcinomas, undifferentiated carcinomas, and lymphoepitheliomas. Tumor initiation has been linked to the Epstein-Barr virus and, in some geographical regions, to alimentary factors. Possible hereditary components for the appearance of NPCs have not yet been clearly identified. In this study, genetic sensitivity to the genotoxic effects of carcinogenic xenobiotics as an endogenous risk factor of tumor initiation was investigated. The single cell microgel electrophoresis assay was used to quantify chemically-induced DNA damage in lymphocytes of 30 NPC patients and 30 non-tumor donors. The xenobiotics investigated were N ′-nitrosodiethylamine, sodium dichromate, and nickel sulphate, with N -methyl- N ′-nitro- N -nitrosoguanidine (MNNG) and dimethyl sulfoxide (DMSO) as positive and negative controls, respectively. The extent of DNA migration in the solvent control cultures was not significantly different between the two groups (1.2±0.5 mean Olive tail moment and standard deviation of 30 individuals for NPC patients; 1.1±0.4 for non-tumor donors). With constant exposure and electrophoretic conditions, genotoxic effects of varying degrees were induced by the different xenobiotics in tumor and non-tumor patients (nickel sulphate: 7.1±2.5 for NPC patients and 5.9±1.6 for non-tumor donors; sodium dichromate: 18.1±5.3 for NPC patients and 16.2±5.4 for non-tumor donors; MNNG: 47.8±13.3 for NPC patients and 52.7±13.6 for non-tumor donors). Only N ′-nitrosodiethylamine proved to induce significantly more DNA migration in lymphocytes of tumor patients (9.8±3.1) as compared to non-tumor patients (8.2±2.3). Although for sodium dichromate the degree of DNA migration did not significantly differ, variability in migration patterns proved to be lower in the tumor group. Mutagen sensitivity of NPC patients was shown to be elevated for a selected xenobiotic, whereas a general elevation of DNA fragility was not present. Further studies on mutagen sensitivity as an endogenous risk factor influencing the susceptibility of patients at the time of first diagnosis of nasopharyngeal carcinomas are warranted.
8 citations
Patent•
28 May 2001
TL;DR: In this paper, the problem of providing a tinned steel sheet which has excellent oxidation resistance, and in which a tin oxidized layer is hardly formed, and a production method therefor, is solved.
Abstract: PROBLEM TO BE SOLVED: To provide a tinned steel sheet which has excellent oxidation resistance, and in which a tin oxidized layer is hardly formed, and a production method therefor. SOLUTION: In the thinned steel sheet having excellent oxidation resistance, one side or both sides of a steel sheet are provided with a tinned layer as an under layer, and, as an over layer, a chemical conversion film consisting of phosphate containing chromium hydrated oxide and magnesium ions, and preferably, containing metal chromium is further provided. In its production method, after the application of electrotinning on one side or both sides of the steel sheet, the steel sheet is dipped into a sodium dichromate aqueous solution. The steel sheet is further dipped into an aqueous solution of pH 2 to 3.5 containing phosphoric ions and magnesium ions, and the liquid is removed from the steel sheet. Then, the steel sheet is heated at 70 to 200 deg.C.
4 citations
Patent•
10 Feb 2001
TL;DR: In this article, lignosulfonate (100 wt parts) is preliminarily acidified with sulfuric acid to pH 1.5-3.5, then half the design amount of ferric sulfate (1.0-9.0 wt part) and the rest of the remaining half are consecutively added and entirely dissolved at stirring for 3-4 h at 60-95 C, after which sodium hydroxide is added to pH 4-5.
Abstract: drilling fluids. SUBSTANCE: lignosulfonate (100 wt parts) preliminarily acidified with sulfuric acid to pH 1.5-3.5 is mixed with half design amount of ferric sulfate (1.5-5.0 wt parts), which is dissolved at 35-40 C. Then design amount of sodium dichromate (4.0-9.0 wt parts) and the rest of ferric sulfate are consecutively added and entirely dissolved at stirring for 3-4 h at 60-95 C, after which sodium hydroxide is added to pH 4-5. EFFECT: increased effect of reagent on filtration and structural- mechanical (thinning) properties of drilling fluid and increased heat resistance thereof to 180 C at lower toxicity due to lesser amount of chromium(VI). 4 tbl
1 citations
TL;DR: In this article, a new procedure with easy product extraction, based on the reaction of 2-acetylfluorene with sodium dichromate in acetic acid, was proposed.
Abstract: 9-Oxofluorene-2-carboxylic acid has been obtained with a yield as high as 98.5%, following a new procedure with easy product extraction, based on the reaction of 2-acetylfluorene with sodium dichromate in acetic acid.