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Results for “Methylurea Compounds”

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At least 415 records · Page 23Linked to original sources
PubMed1990

Genotoxic effect of isoproturon (herbicide) as revealed by three mammalian in vivo mutagenic bioassays.

Genotoxic effect of isoproturon was assessed by employing in vivo chromosomal aberration, micronucleus and sperm-shape abnormality assays. A significant dose-responsive mutagenic effect was observed in chromosome aberration and sperm-shape abnormality tests whereas in micronucleus assay the effect was significant only at the highest dose (200 mg/kg). Only the result for the chronic dose and the two different fixation times (6 and 48 hr) were not statistically significant. The results indicate the genotoxic property of isoproturon in mammalian in vivo test system.

Analysis of Variance↗
PubMed1989

Chemical modification of bovine pancreatic trypsin inhibitor for single site coupling of immunogenic peptides for NMR conformational analysis.

Procedures for chemical modification of bovine pancreatic trypsin inhibitor (BPTI) to allow site-specific coupling of immunogenic peptides are reported. Each of the modified proteins has a single free amino group; the other amino groups of lysine or the amino terminus are blocked by acetylation or guanidination. Two of the derivatives were prepared by protecting Lys-15 by complexation with trypsin or chymotrypsin during acetylation with N-hydroxysuccinimide acetate or guanidination with 3,5-dimethylpyrazole-1-carboxamidine nitrate. A third derivative with a free amino group at the amino terminus was prepared by guanidination of the 4 lysine residues with o-methylisourea. The purity and structural integrity of the modified proteins was checked by NMR spectroscopy. Cysteine-containing peptides can be coupled to the single free amino group using several heterobifunctional linking reagents. N-Succinimidyl 3-(2-pyridyldithio)propionate is the most satisfactory coupling reagent for NMR studies because of its high specificity. Two-dimensional NMR spectroscopy shows that the conformation of the modified proteins is almost identical with that of native BPTI. The BPTI derivatives are suitable for use as models for NMR investigations of the conformation of immunogenic peptides conjugated to a carrier protein.

Acetylation↗
PubMed1989

[Changes in the adhesiveness between enterocytes after short-term blastomogenic exposures].

Following short-term local applications of high doses of N-methyl-N-nitrozourea and 7,2-dimethylbenz(a)antracen, the intercellular adhesion in the distal colon epithelium of ice retains increased at least for a month. The magnitude of this shift and its duration ops both with moving away from the area of application, or with reducing the doses of carcinogens to be closely related to the frequency of tumour production in the site of epithelium under chronic local applications of N-methyl-N-nitrozourea. After the application of noncarcinogenic methylurea or the subcutaneous injection of 1,2-dimethylhydrazine to the mice resistant to its carcinogenic action the wavy fluctuations of the magnitude of intercellular adhesion disappear within a week. The following conclusion can be drawn from the results: the long-term increase in enterocyte-enterocyte adhesion may be an earlier sign of the colon epithelium reaction to carcinogenic action.

1,2-Dimethylhydrazine↗
PubMed1988

[Prevention using ascorbic acid, hexamethylenetetramine and sodium metabisulfite of the blastomogenic effect caused by the combined administration into the stomach of mice of sodium nitrite with methylurea or with aminopyrine].

It was shown in experiments on 186 mice that formation of tumors of the lung and fore-stomach induced by injection of sodium nitrite in combination with aminopyrine or methylurea is inhibited following treatment with ascorbic acid, hexamethylenetetramine or sodium metabisulfite.

Aminopyrine↗
PubMed1987

[Clinico-experimental research on acute isoproturon poisoning in sheep].

The toxic action of the carbamide preparation isoproturon-50 was followed up after oral administration at a single dose rate of 3600 mg per kg body mass. Studied were also the clinical picture, body temperature, pulse rate and respiratory excursions, appetite, general behaviour and such biochemical indices as calcium, phosphorus, magnesium, carotene, vitamin A, blood sugar, total protein, aspartate aminotransferase and alanine aminotransferase.

Acute Disease↗
PubMed1979

Protection against alloxan-induced diabetes by various urea derivatives: relationship between protective effects and reactivity with the hydroxyl radical.

Several urea derivatives (monomethylurea, monoethylurea and diethylurea) give i.p. to mice 30 min before alloxan (75 mg/kg i.v.) were able to prevent the diabetogenic actions of alloxan. Protection by these agents correlated reasonably well with their capacity to react with (scavenge) the hydroxyl radical. Protection did not correlate with the capacity of the above agents to cause a transient hyperglycemia at the point of alloxan administration, which might have also been a potential means of protection. These data extend previously published data on the capacity of hydroxyl radical scavengers to protect against alloxan and add evidence to the concept that the hydroxyl radical, generated within the beta cells, is the species derived from alloxan responsible for the damage to beta cells.

Animals↗