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At least 451 records · Page 25Linked to original sources
PubMed1995

Toxicity of cotoran (fluometuron) in Desert sheep.

Twelve of fifteen 6-9-mo-old clinically healthy Desert sheep were given single or repeated daily doses of 25 to 4000 mg cotoran/kg by drench. Cotoran poisoning was characterized by grinding of the teeth, ruminal tympany, mydriasis, dyspnea, staggering, paresis of the hind and forelimbs, and recumbency. Lesions were widespread congestion and hemorrhage, hepatic fatty change, catarrhal enteritis and degeneration of the epithelial cells of the renal proximal convoluted tubules. These were accompanied by significant increases in the activities of GOT, LDH and GGT and decreases in serum total protein and calcium.

Abomasum↗
PubMed1995

Developmental toxicity of the substituted phenylurea herbicide isoproturon in rats.

Isoproturon, a substituted phenylurea herbicide, was studied for its toxicity to dams and its potential fetotoxic/teratogenic effects in the fetuses of albino rats. Isoproturon technical administered orally at 45, 90 or 180 mg/kg/d to dams during d 6-20 of pregnancy did not produce maternal toxicity at 45 or 90 mg/kg/d. However, 180 mg isoproturon/kg/d caused changes in maternal enzymes and chromatid breaks. There was no fetotoxic/teratogenic effect of isoproturon at the tested dosage levels in number of implantations, percent resorption, fetal weights, and external, visceral and skeletal fetal observations.

Animals↗
PubMedDate not supplied

[Polarized immunofluorescent analysis of the herbicide isoproturon].

Polarographic fluoroimmunoassay was developed for estimation of residual amounts of the herbicide isoproturon . The procedure is simple, accurate, highly sensitive and allows 10 preparations to be tested within approximately 7 min; the sample volume was 50 microliters and the low limit of the procedure sensitivity was about 0.2 micrograms/ml. The polarographic immunoassay may be used in screening express controls of isoproturon concentration in the sewage or in various extracts from various sources to control the herbicide contamination.

Fluorescence Polarization Immunoassay↗
PubMed1993

Neurotoxicity of isoproturon, a substituted phenylurea herbicide, in mice.

Effects of single oral administration of isoproturon (0.5, 1.0 and 2.0 g/kg) on CNS of male mice were studied. At higher doses, spontaneous motor activity (SMA) and forced locomotor activity (FLA) were reduced. Reduction of SMA and FLA was lesser than the reference drug-chlorpromazine hydrochloride (Ch. HCl; 15 mg/kg). Isoproturon, at all doses, potentiated both pentobarbital and barbital-induced sleeping time. At higher doses, potentiation of pentobarbital-induced hypnosis was comparable to Ch.HCl but isoproturon was more effective in inducing hypnosis with barbital. Isoproturon could not protect mice against amphetamine-induced aggregation toxicity. Isoproturon exhibited anticonvulsant activity against both supramaximal electroshock seizures and pentylenetetrazol-induced convulsions. It had no anticonvulsant activity against strychnine but only caused delay in onset of and protection from mortality. At higher doses, anticonvulsant action of isoproturon was comparable to diphenylhydantoin (50 mg/kg) and phenobarbital sodium (100 mg/kg). The study reveals that isoproturon has distinct inhibitory effect on central motor performance and sedative action on CNS. And also it has anticonvulsive and protective actions.

Amphetamine↗
PubMed1993

Changes in protein stability upon chemical modification of lysine residues of bovine serum albumin by different reagents.

Using acetic anhydride, potassium cyanate and O-methyl isourea six chemically modified derivatives of bovine serum albumin with chemical modification on lysine side chains have been prepared. All the modified preparations were found to be homogeneous with respect to size and charge. Size exclusion chromatography on a calibrated Sephacryl S-300 column revealed that whereas acetylation and carbamylation produce significant increase in Stokes' radius, guanidination produces a slight decrease in Stokes' radius. Stability of native and different modified preparations was studied by following urea induced denaturation using the technique of uv difference spectroscopy and by measuring delta GDH2O and delta delta GD(urea)50% from these data. The order of stability of different preparations was found to be guanidinated > native > carbamylated > acetylated.

Acetic Anhydrides↗
PubMed1994

Different types of angiotensin II receptor antagonism induced by BIBS 222 in the rat portal vein and rabbit aorta; the influence of receptor reserve.

BIBS 222, a nonpeptide benzimidazole derivative, displayed insurmountable angiotensin II (Ang II) receptor antagonism in the rabbit aorta (pKB = 7.9), whereas it antagonized Ang II-induced phasic contractions in the rat portal vein in a surmountable manner (pA2 = 8.7, slope = 1.02). The mechanism of the different types of antagonism induced by BIBS 222 in vascular preparations was investigated. Using the slowly dissociating Ang II receptor antagonist sarile, we found that the calculated KA values for Ang II in the rat portal vein and in the rabbit aorta were different (6.0 x 10(-8) M vs. 2.0 x 10(-9) M). The estimated receptor reserve at the maximal response for the effect of Ang II in the rat portal vein amounts to 63%, whereas in rabbit aortic rings it is about 9%. In the presence of the disulfide-reducing agent dithiothreitol (0.5 mM), which led to the inactivation of about 70% of the Ang II receptors in the rat portal vein, BIBS 222 (10(-6) M) shifted the concentration-response curve for Ang II to the right and reduced the maximal response by 24 +/- 4.4% (P < .05). In conclusion, rat portal vein possesses a larger receptor reserve for Ang II than rabbit aortic rings. The surmountable Ang II receptor antagonism induced by BIBS 222 may be caused by the large receptor reserve in this preparation. Alternatively, different KA values for Ang II in these tissues may suggest the existence of two subpopulations of Ang II subtype 1 receptors, accounting for the cross-tissue behavior of BIBS 222.

Angiotensin Receptor Antagonists↗
PubMed1994

Toxic effects of dimethylthiourea in rats.

Dimethylthiourea (DMTU) is a small, highly diffusible molecule that effectively scavenges toxic oxygen metabolites in vitro and reduces oxidative injury in many biologic systems. Nonetheless, for unknown reasons, DMTU has occasionally failed to decrease damage in some systems where injury is presumed to be mediated by oxygen metabolites. We hypothesized that the inconsistent pattern of protection might partially reflect a direct toxicity of DMTU. Our results supported this premise. We found that rats treated with commonly used doses of highly purified DMTU had increased lung accumulation of intravenously injected iodine 125-labeled albumin (4 hours after DMTU treatment) and decreased blood glutathione levels (24 hours after DMTU treatment) when compared with saline-injected control rats. In contrast, rats treated with dimethylurea, a analog of DMTU, did not develop increased accumulation of labeled albumin in the lungs or decreased blood glutathione levels. We conclude that DMTU has intrinsically toxic effects in rats and that DMTU toxicity may at times obscure its protective action.

Animals↗
PubMed1977

[Inhibitory effect of a number of substances on manifestation of the embryotoxic and teratogenic effects of methylurea and sodium nitrite].

Embryos died and a teratogenic effect followed combined intragastric administration of methylurea (MU) and sodium nitrite (SN) to rats on the 9th day of pregnancy; this was caused by the endogenous synthesis of nitroso-methylurea which produced a pathogenic action. Ascorbic acid and urotropine completely blocked the possibility of manifestation of the embryotoxic and teratogenic effect occuring after combined administration of MU and SN. Sodium sulfomate decreased the embryotoxic and partially the teratogenic effect considerably, whereas urea failed to prevent the expression of the harmful effect of MU and SN on the embryo.

Abnormalities, Drug-Induced↗
PubMed1997

[Chemical accident with isoproturone in an industrial plant in Frankfurt am Main 27 January 1996].

On 27 January 1996, about 1 ton of Isoproturone was released into the atmosphere due to an accident in a chemical plant located at Frankfurt-Griesheim, Germany. A nearby residential area was contaminated by up to 500 mg Isoproturon/m2. According to the published toxicological data and the contamination data, model calculations were performed demonstrating that the individual exposure remained below the LOEL. For better exposure and risk assessment urine biomonitoring was offered to the residents. HMEPMH, the main metabolite of Isoproturon was detected in 12% (19/154) of the participants in the test, with a maximum value of 14.2 micrograms/l, i.e. the internal exposure remained even below ADI. Control tests demonstrated the decrease of the soil contamination after some weeks, and by June 1996 Isoproturone was no longer detectable, neither in soil nor in vegetables.

Accidents, Occupational↗
PubMed1976

Molecular and cellular effects of antisickling concentrations of alkylureas.

Alkylureas are capable of inhibiting sickling in vitro and the gelation of solutions of hemoglobin S at concentrations between 0.05 and 0.1 M with increasing effectiveness that is directly proportional to the length of the alkyl chain (butyl greater than propyl greater than ethyl greater than methyl). 6The inhibitory effect is independent of pH between 6.5 and 7.5 and is a process driven by entropy. The alkylureas at concentrations of 0.1 M have minimal effects on several erythrocyte functions. Oxygen equilibria, osmotic fragility, reduced glutathione content, and glutathione reductase activity are totally unaffected, while pyruvic kinase activity is decreased only by butylurea by about 20%, and glucose-6-phosphate dehydrogenase activity is decreased progressively to a maximum of 30% in direct proportion to the length of the alkyl chain. Alkylureas not only inhibit sickling but are also capable of desickling erythrocytes that have been maintained in the deoxygenated state. They have little effect on several erythrocyte functions at antisickling concentrations, but their toxicity must be evaluated before they can be examined as potential therapeutic agents for the treatment or prevention of acute episodes in sickle cell anemia.

Erythrocytes, Abnormal↗
PubMed1983

The intragastric host-mediated assay for the assessment of the formation of direct mutagens in vivo.

The intragastric host-mediated assay (h.m.a.) was devised and carried out with a view to assessing the formation of direct mutagens in the gastrointestinal tract of mammals. The h.m.a. consists in the injection of nitrosable compounds, NaNO2 and cells of the yeast S. pombe, by gavage into the animals' stomachs and in the recovery of the target cells from the faeces for mutation-induction analysis. Methylurea was chosen as a model nitrosable compound, and the effects of nitrosation modulators such as ascorbic acid and thiocyanate were studied. Cimetidine, a drug nitrosable in vitro, was tested with the system. Positive results were obtained only at very large doses and in artificially produced low pH. The new host-mediated assay seems to be efficient in revealing the formation, in vivo, of direct, short-living mutagens.

Animals↗
PubMedDate not supplied

In vivo mammalian metabolism of methylamine and methylurea and their metabolic interrelationship.

The metabolism of methylamine has been investigated in the rabbit and rat, and evidence has been presented to show that the metabolism of the compound leads to the formation and excretion of methylurea, a metabolite suspected, but never conclusively shown, to exist by previous investigators. Urinary methylurea, after the administration of methyl-14C-amine, was shown to have 14C activity at both the carbonyl and methyl portions (groups) of the molecule. 14C activity in the carbonyl group of methylurea was derived from the same metabolic CO2 pool that is used in the formation of urinary urea and respiratory carbon dioxide. Administration of methyl-14C-amine led to the formation of respiratory 14CO2, as noted by various investigators, and it was shown that during a 24-hr period the ratio of specific activity (urea/respiratory CO2) approached 1, in agreement with previous data reported by Mackenzie and du Vigneaud [J. Biol. Chem. 172, 353-354 (1948)]. In order to quantitatively investigate some aspects of metabolism of methylurea, a procedure was developed for the convenient synthesis of N-methyl-14C-carbonyl-urea. In a series of experiments, the urinary urea of the animals injected with N-methyl-14C-carbonyl-urea and N-methyl-14C-urea was examined for radioactivity. Only limited amounts of 14C activity were found in the carbonyl group of urea following administration of N-methyl-14C-urea. However, after the administration of N-methyl-14C-carbonyl-urea, urinary urea contained a 200-fold excess of 14C activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗