Biomedical subjects

W Lijinsky

Publications and source records attributed to W Lijinsky.

At least 253 records · Page 14Linked to original sources

PubMed1975

Carcinogenicity of methylated nitrosopiperidines.

The carcinogenicity of nitrosopiperidine and five methylated derivatives was compared by feeding them to rats at equimolar concentrations in drinking water, at the rate of 20 ml per day, 5 days a week. The maximum treatment time was 50 weeks. Nitrosopiperidine, 2-methyl-, 3-methyl- and 4-methyl-nitrosopiperidine induced tumors of the nasal turbinates or upper gastrointestinal tract in almost 100% of the animals. There was a significantly longer time to death from these tumors in the group treated with 2-methylnitrosopiperidine and a number of hepatocellular carcinomas appeared in this longer lived group. Very few tumors of these sites were seen in rats treated with 2,6-dimethyl- or 2,2,6,6-tetramethyl-nitrosopiperidine. It was concluded that blockage by methyl groups of one or more carbon atoms alpha to the nitroso function in nitrosopiperidine significantly reduces carcinogenic activity of the molecule.

Animals↗

PubMed1975

Induction of neurogenic tumors by nitrosotrialkylureas in rats.

Four nitrosotrialkylureas were each fed to groups of 15 male and 15 female Sprague-Dawley rats for 50 weeks in drinking water at the same molar concentration. Tumors of nervous origin arose after treatment with nitrosotrimethylurea (3/30), notrosotriethylurea (7/30), nitrosomethyldiethylurea (23/30), and nitrosoethyldimethylurea (8/30). A comparison of the relative stabilities of the four nitrosoureas in aqueous solution at various pH's showed no correlation with the tumorigenicities of the compounds.

Animals↗

PubMed1975

Tumorigenesis by oxygenated nitrosopiperidines in rats.

Three oxygenated N-nitrosopiperidines--nitroso-3-piperidinol, nitroso-4-piperidinol, and nitroso-4-piperidone--were prepared and given in drinking water at equivalent molar doses to Sprague-Dawley rats. All were potent carcinogens, 100% of the rats developed tumors in all treatment groups. Nitroso-3-piperidinol resembled nitrosopiperidine in inducing a high incidence of tumors of the nasal cavity and upper alimentary tract, and a few liver tumors. Nitroso-4-piperidinol and nitroso-4-piperidone caused a high incidence of tumors of the nasal cavity but very few tumors of the upper alimentary tract. After treatment with the 4-substituted compounds, a high incidence of liver tumors was observed in females but not in males.

Animals↗

PubMed1975

Tumor induction in rats by feeding heptamethyleneimine and nitrite in water.

Groups of 15 males and 15 females Sprague-Dawley rats were given 20 ml of drinking water solution containing either 0.2% heptamethyleneimine hydrochloride or this salt together with 0.2% sodium nitrite, 5 days a week for 28 weeks. Another group of 17 male and 30 female rats was given 0.2% sodium nitrite solution for 104 weeks. Most of the animals given heptamethyleneimine hydrochloride or sodium nitrite alone survived 2 years or more after the beginning of the treatment, and no tumors attributable to the treatment were seen at death; tumors appearing were those of endocrine origin found commonly in untreated controls. In the group receiving the combined treatment, most females were dead at 50 weeks and most males were dead at 80 weeks, 27 of 30 having tumors not seen in either control group. A total of 16 had squamous carcinomas in the lung; 25 had tumors of the oropharynx, tongue, esophagus, and forestomach; and there were a few animals with tumors in the nasal cavity and trachea. The expericment showed that squamous tumors of the lung could be induced by ingestion an amine and sodium nitrite.

Animals↗

PubMed1975

Induction of urinary bladder tumors in rats by administration nitrosomethyldodecylamine.

Nitrosomethyl-n-dodecylamine, a product of the reaction of dimethyl-n-dodecylamine with nitrous acid, was given to Sprague-Dawley rats by gavage in olive oil solution. Twice-weekly treatments with 12 mg of the nitrosamine for 50 weeks gave rise to 100% incidence of transitional cell carcinomas of the urinary bladder. In contrast with the tests of other N-nitroso compounds, this compound seemed to be more effective in males than in females; females died later with the tumor although the dose per unit body weight was higher in females than in males.

Animals↗

PubMed1975

Increased carcinogenicity of 2,6-dimethylnitrosomopholine compared with nitrosomopholine in rats.

Nitrosomorpholine was given to rats in drinking water at the rate of 4 mg/week for 30 weeks. Tumors of the liver were induced in 53% of treated animals and were of both hepatocellular and Kupffer cell origin. One-half of the treated animals were alive 75 weeks after the beginning of treatment, but only 2 survived to 104 weeks. 2,6-Dimethylnitrosomopholine was given to rats at the same molar concentration in drinking water for 30 weeks (5 mg/week). All of these animals died with tumors within 34 weeks after the beginning of treatment; these tumors were mainly in the esophagus and nasal turbinates, and only 1 liver tumor was seen. This greatly changed tumorigenicity of the dimethyl compound might be due to steric factors or to enhanced reactivity at the positions alpha to the nitroso function induced by the methyl groups at the beta position.

Animals↗

PubMed1975

Carcinogenicity of N-nitroso-3,4-dichloro- and n-nitroso-3,4-dibromopiperidine in rats.

The carcinogenic potencies of 3,4-dichloro- and 3,4-dibromonitrosopiperdine were compared with that of nitrosopiperidine by feeding to groups of 15 male rats in drinking water. A treatment of 15 weeks with a total of 0.5 mmole of the dichloro compound led to death of all animals before 24 weeks with tumors of the tongue, pharynx, esophagus, nonglandular stomach, nasal turbinates, trachea, bronchi, and bronchioles. Treatment of 27 weeks with the dibromo compound, a total of 1.0 mmole, caused death of all the animals by 41 weeks, with the same types of tumors. One-half of the rats treated with an almost 3-fold higher daily dose of nitrosopiperidine, 3.9 mmoles total, were alive at 40 weeks, and all were not dead until 55 weeks. Most of these animals died with tumors of the tongue, pharynx, esophagus, and nonglandular stomach and with squamous cell tumors and olfactory carcinomas of the nasal cavity, but there were no tumors of the respiratory tree. Substitution of chlorine or bromine in nitrosopiperidine greatly increased the carcinogenicity of the compound.

Animals↗

PubMed1974