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M Y Farooqui

Publications and source records attributed to M Y Farooqui.

At least 19 recordsLinked to original sources
PubMed1993

Metabolism of allylnitrile to cyanide: in vitro studies.

In liver fractions from male Sprague-Dawley rats, the metabolism of allylnitrile (ALN) to cyanide (CN-) was localized in the microsomal fraction and required NADPH and oxygen for maximal activity. The biotransformation of ALN to CN- was characterized with respect to time, microsomal protein concentration, pH and temperature. Metabolism of ALN was increased in microsomes obtained from phenobarbital-treated rats (160% of control) and decreased with cobaltous chloride and beta-diethyl aminoethyl-2,2-diphenyl pentanoate (SKF 525-A) treatments (48% of control). Addition of SKF 525-A to the incubation mixtures inhibited ALN metabolism to CN-. Addition of the epoxide hydrolase inhibitor, 1,1,1-trichloropropane 2,3-oxide, decreased the formation of CN- from ALN. Addition of glutathione, cysteine, D-penicillamine, and 2-mercaptoethanol enhanced the release of CN- from ALN. These findings indicate that ALN is metabolized to CN- via a cytochrome P-450-dependent mixed-function oxidase system.

Animals↗
PubMed1991

The urotoxic effects of N,N'-dimethylaminopropionitrile. 2. In vivo and in vitro metabolism.

The urotoxicity and metabolism of N,N'-dimethylaminopropionitrile (DMAPN) were investigated in male Sprague-Dawley rats. Animals treated with 525 mg DMAPN/kg or equimolar doses of commercially available potential DMAPN metabolites showed varying levels of urinary retention. About 44% of the administered dose of DMAPN was excreted unchanged in 5 days. beta-Aminopropionitrile and cyanoacetic acid were identified as urinary metabolites. The urinary excretion of cyanoacetic acid was nonlinearly proportional to the volume of urine retained in the bladders. In vitro, the metabolism of DMAPN to cyanide, formaldehyde, and cyanoacetic acid was localized mostly in the microsomal fraction of liver, kidney, and urinary bladders. This reaction required NADPH and oxygen for maximal activity. Metabolism of DMAPN was increased in hepatic microsomes obtained from phenobarbital-treated rats (220% of control) and decreased following CoCl1 treatments (73% of controls). Addition of SKF 525-A to the incubation mixtures inhibited the metabolism of DMAPN to formaldehyde (47-64% of controls). Addition of sulfhydryl compounds (glutathione and cysteine) to the incubation mixtures did not affect the rate of these reactions. These findings indicate that DMAPN is primarily metabolized via a cytochrome P450-dependent mixed-function oxidase system and that the urotoxic effects of DMAPN may be related to this metabolism.

Acetates↗
PubMed1991

Toxicology of methacrylonitrile.

The chemistry, industrial usage, general toxicity and experimental use of methacrylonitrile are briefly reviewed. Methacrylonitrile, a reactive, unsaturated and methylated aliphatic nitrile, has industrial applications in a variety of organic processes related to the polymer industry. Its general toxic effects are primarily related to the release of cyanide and formation of reactive metabolites containing a double bond between carbon 2 and 3. Methacrylonitrile has been given by a variety of routes to mammalian species to study its toxic effects. More recent in vivo and in vitro experimental work concerning its toxicity and metabolism are summarized and possible mechanisms of this chemical's toxic action are discussed.

Animals↗
PubMed1991

Studies on the mechanism of urotoxic effects of N,N'-dimethylaminopropionitrile in rats and mice. 1. Biochemical and morphologic characterization of the injury and its relationship to metabolism.

N,N'-Dimethylaminopropionitrile (DMAPN), a major component of the NIAX catalyst ESN, is known to cause urinary bladder dysfunction in exposed workers. In order to investigate the mechanism of DMAPN toxicity, we carried out time-course (0-72 h) and dose-response (175-700 mg/kg) studies on the effects of DMAPN in rats and mice. Treated animals exhibited several signs of toxicity including loss of body weight, reduced water consumption, and bladder urine retention, as well as bladder injury. DMAPN-induced bladder injury was characterized by distended bladders with marked diffuse submucosal and subserosal edema, petechial hemorrhage, and multifocal perivascular inflammatory infiltrates. The qualitative and quantitative analysis of urine indicated hypoosmolality, aciduria, hematuria, proteinuria, and oliguria. Elevated levels of creatinine and urea levels in plasma were indicative of renal dysfunction. Within hours following DMAPN administration, the animals exhibited a significant increase in urinary retention that resolved between 60 and 72 h. Rats excreted about 44% of the administered DMAPN dose unchanged in the urine, while mice excreted only about 6% of the dose. Commercially available DMAPN metabolites, administered by gavage, produced toxic effects less adverse than DMAPN. The biochemical effects of DMAPN included depletion of glutathione and increased lipid peroxidation in target organs, including urinary bladder and kidney. These studies indicate that there are species differences in DMAPN toxicity. The differences may be due to differences in the formation of reactive metabolic intermediates of DMAPN.

Aminopropionitrile↗
PubMed1990

Metabolism of methacrylonitrile to cyanide: in vitro studies.

In liver fractions from male Sprague-Dawley rats, the metabolism of methacrylonitrile (MeAN) to cyanide (CN-) was localized in microsomal fraction and required reduced nicotinamide adenine dinucleotide phosphate (NADPH) and oxygen for maximal activity. The biotransformation of MeAN to CN- was characterized with respect to time, microsomal protein concentration, pH, and temperature. Metabolism of MeAN was increased in microsomes obtained from phenobarbital-treated rats (310% of control) and decreased with CoCl2 and SKF 525 A treatments (55% and 61%, respectively). Addition of the epoxide hydratase inhibitor, 1,1,1-trichloropropane 2,3-oxide, decreased the formation of CN- from MeAN. Addition of glutathione, cysteine, D-penicillamine, and 2-mercaptoethanol enhanced the released of CN- from MeAN. These findings indicate that MeAN is metabolized to CN- via a cytochrome P-450-dependent mixed-function oxidase system.

Animals↗
PubMed1990

Hemoglobin degradation, lipid peroxidation, and inhibition of Na+/K(+)-ATPase in rat erythrocytes exposed to acrylonitrile.

The effect of acrylonitrile (VCN) on erythrocyte lipid metabolism was investigated in vitro in metabolically active red cells from male Sprague-Dawley rats containing three types of hemoglobins: oxyhemoglobin, methemoglobin, and carbon monoxyhemoglobin. VCN at the concentration of 10 mM rapidly depleted erythrocyte glutathione (GSH) (75% of control) and induced lipid peroxidation (274% of control). Degradation of oxy- and methemoglobin was directly proportional to the extent of lipid peroxidation (r = 0.89). Addition of glucose to the incubation medium decreased hemoglobin degradation while it slightly increased VCN-induced lipid peroxidation. The highest amount of lipid peroxidation occurred in erythrocytes containing carbon monoxyhemoglobin and glucose. In the isolated red cell membranes incubated with 10 mM VCN, the lipid peroxidation was 400% of controls. VCN (25 mM) noncompetitively inhibited erythrocyte membrane Na+/K(+)-ATPase activity and the degree of inhibition was inversely proportional to the reaction temperature (r = -0.88). These findings indicate that the VCN induced hemoglobin degradation and lipid peroxidation are two extremes of a spectrum of oxidative damage in red cells leading to a change in physical state of membrane structure causing inhibition of adenosine triphosphate (ATPase) activity.

Acrylonitrile↗
PubMed1990

Toxicity and tissue distribution of methacrylonitrile in rats.

The toxicity, uptake, tissue distribution, elimination, and covalent binding of 2-[14C]methyl-[2.3-14C]acrylonitrile (MeAN) in male Sprague-Dawley rats were investigated. Following an oral administration of 100 mg/Kg body weight (0.5 LD50, 8 microCi/Kg bw) the rats exhibited several signs of toxicity including ataxia, convulsions, mild diarrhea, salivation, lacrimation, and bladder urine retention. The treated animals excreted 43% of the 14C in the urine, 14% in the feces, and 2.5% in the expired air as 14CO2 in 10 days. Hydrogen cyanide was not detectable. Red blood cells retained significant amounts of radioactivity for more than 10 days after treatment. MeAN was extensively absorbed through the gastrointestinal tract and distributed in all the tissues of the rats. The major concentrations of the radioactivity were found with up to 25% of the administered dose in bone, liver, spleen, kidney, blood, and the gastrointestinal tract. This study indicates that MeAN is rapidly absorbed and distributed and the major route of excretion is urinary.

Air↗
PubMed1989

Disposition of methacrylonitrile in rats and distribution in blood components.

The interaction of 2[14C]methyl-2,3[14C]acrylonitrile (MeAN) with the components of blood and its disposition in male Sprague-Dawley rats has been investigated. Following an oral administration of 100 mg/kg (0.5 LD50, 8 microCi/kg), the rats excreted 43% of the [14C] in the urine, 15% in the feces and 2.5% in the expired air as 14CO2 in 5 days. Hydrogen cyanide (H14CN) was not detectable. The red blood cells retained significant amounts of radioactivity for more than five days after administration, whereas the [14C]-activity in plasma declined sharply. More than 50% of the radioactivity in erythrocytes was detected as covalently bound to cytoplasmic (hemoglobin) and membrane proteins. A small amount of radioactivity was also found in the heme fraction. About 13% of the total dose administered was recovered as thiocyanate in the plasma and the urine. These results suggest that the toxicity of MeAN may be attributable to the whole molecule and not entirely to the in vivo liberation of cyanide.

Acrylates↗
PubMed1988

Interaction of methacrylonitrile with glutathione.

The interaction of methacrylonitrile (MeAN) with glutathione (GSH) was evaluated in aqueous solution and its in vivo potential to deplete GSH in male Sprague Dawley rats at the 0.5 LD50 dose of 100 mg MeAN/Kg body weight was investigated. Addition of MeAN (0-40 mM) to a solution of 0.3 mM GSH in 2 mM EDTA, pH 7.4, resulted in a time and concentration dependent depletion of GSH determined as nonprotein sulfhydryl. Thin layer chromatography analysis of incubation mixtures of MeAN with GSH and cysteine showed the appearance of distinct spots representing the adducts S-cyanopropyl GSH and S-cyanopropyl cysteine. Oral administration of MeAN to the rats resulted in significant depletion of GSH in the liver, kidney, heart, lung, brain and spleen. The maximum GSH depletion was noticed in the liver (approximately 39% of control) and in other organs it ranged between 26-34% of control. It is likely that the toxicity of MeAN may be related to in vivo GSH depletion.

Acrylates↗
PubMed1987

Glutathione and lipid peroxidation in the aging rat.

1. Tissue extracts were prepared from liver, kidney, heart, brain, lung and spleen of male Sprague-Dawley rats of different ages (1-36 months); each of the extracts was analyzed for reduced glutathione (GSH) and lipid peroxides. 2. At all ages the GSH content in the liver was 3-10 times higher than that in other tissues. 3. In the old (36 months) rat the GSH content of all the tissues studied were lower (35-60%) than that in 2.5 month old rat. 4. The lipid peroxides levels increased by age in all tissues studied. 5. These findings indicate that general characteristics of aging tissue may include a decrease in GSH content and increase in lipid peroxides showing a decrease in reducing potential in senescence.

Aging↗
PubMed1986

Influence of intraperitoneally administered formaldehyde on bile production and tissue glutathione levels in rats.

The influence of formaldehyde on bile secretion and tissue glutathione concentrations was investigated in male Sprague Dawley rats following a sublethal intraperitoneal administration (72 mg/kg). Within 2-3 h of administration formaldehyde caused a 2-fold increase in secretion of bile and significant decrease in the levels of glutathione in liver (39% of control) followed by kidney (33%), lung (31%) and brain (22%). The results indicate a possible protective role of glutathione in the toxicity of formaldehyde.

Animals↗
PubMed1984

Circadian periodicity of tissue glutathione and its relationship with lipid peroxidation in rats.

Circadian fluctuations in tissue glutathione (GSH) concentrations and lipid peroxidation in male Sprague-Dawley rats were investigated. Blood and all the organs studied exhibited distinct circadian variation both in GSH concentrations and peroxidation of polyunsaturated fatty acids. There was a great variation among organs in the periodicity and amplitude of the fluctuations in GSH concentrations. Liver displayed the highest variation (approximately 50%) followed by stomach (approximately 37%), heart (approximately 25%) and kidney (approximately 19%). The changes in other organs were significant but of less magnitude. Implications of such variations and caution in interpretation of experimental results in response to the exposure of animals to xenobiotics are discussed.

Animals↗
PubMed1983

Comparative toxicokinetics of 2,3-14C-and 1-14C-acrylonitrile in the rat.

The tissue distribution, elimination and covalent binding of 2,3-14C-and 1-14C-acrylonitrile (VCN) were studies in male Sprague-Dawley rats given an oral dose of 46.5 mg kg-1. Exhalation of unchanged VCN, 14CO2 and H14CN was monitored at selected intervals. Only 5% of the total dose administered was recovered was unchanged VCN. Rate given 2,3-14C-VCN exhaled only 2% of 14C activity was 14CO2 and none was recovered as H14CN, whereas rats given 1-14C-VCN exhaled about 12% of 14C activity as 14CO2 and 0.5% as H14CN. In the initial 24 h, 40% of radioactivity from 1-14C-VCN appeared in urine, while 60% was recovered in the urine of rats given 2,3-14C-VCN. The red blood cells retained significant amounts of radioactivity from both the compounds for more than 10 days after administration, whereas the 14C activity in plasma declined sharply. The highest level of radioactivity from both compounds was recovered in the gastrointestinal tract. In liver, kidney, brain, spleen, adrenal, lung and heart tissues the unbound percent radioactivity decreased, while irreversible percent covalent binding to macromolecules in relation to total increased concomitantly. Subcellular fractionation of the tissues showed that most of the covalently bound radioactivity was distributed in non-cytosolic fractions. As compared to 1-14C-VCN administered animals, the percentage of covalent binding of 2,3-14C-VCN was significantly higher even 72 h after dosing. The relationship between covalent binding and acrylonitrile toxicity is discussed.

Acrylonitrile↗
PubMed1983

Formaldehyde.

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Animals↗
PubMed1983

In vivo interactions of acrylonitrile with macromolecules in rats.

The irreversible binding of [2,3-14C]acrylonitrile (VCN) to proteins, RNA and DNA of various tissues of male Sprague-Dawley rats after a single oral dose of 46.5 mg/kg (0.5 LD50) has been studied. Proteins were isolated by chloroform-isoamyl alcohol-phenol extraction. RNA and DNA were separated by hydroxyapatite chromatography. Binding of VCN to proteins was extensive and was time dependent. Radioactivity in nucleic acids was registered in the liver and the target organs, stomach and brain. DNA alkylation, which increased by time, was significantly higher in the target organs, brain and stomach (119 and 81 pmol/mg, respectively, at 24 h) than that in the liver. The covalent binding indices for the liver, stomach and brain at 24 h after dosing were, 5.9, 51.9 and 65.3, respectively. These results suggest that VCN is able to act as a multipotent carcinogen by alkylation of DNA in the extrahepatic target tissues, stomach and brain.

Acrylonitrile↗