20 Result(s)
within
R Schoental
Science, Humanities and Social Sciences, multidisciplinary
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Article
Metabolic Products of 3: 4-Benzpyrene
IN 1936, Peacock1 observed that animals receiving intravenous injections of 3: 4-benzpyrene excreted in the bile an alkali-soluble product (BPX) possessing specific fluorescence bands which differed from those of...
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Article
Oxidation of Anthracene by Osmium Tetroxide
WE have shown recently1 that the addition of osmium tetroxide to the 9 : 10-positions of phenanthrene, first observed by Criegee, Marchand and Wannowius2, is a general property in a series of tetra- and penta-cyc...
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Article
Contaminant of Commercial 3 : 4-Benzpyrene
IN their studies of the metabolic products of 3 : 4-benzpyrene, Berenblum and Schoental1 separated by chromatography a material (‘fraction V’) which had a fluorescence spectrum of much shorter wavelength than tho...
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Article
Palatability of N-Oxides of Pyrrolizidine Alkaloids as a Factor in Senecio Poisoning
RECENT chemical studies revealed that pyrrolizidine alkaloids are accompanied in the plants by their N-oxides1. In young growing plants, N-oxides may constitute more than 90 per cent of the alkaloid content, whil...
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Article
Isolation of 3 : 4-9 : 10-Dibenzopyrene from Coal-Tar
BY fractionation of coal-tar on alumina, Berenblum and Schoental1 demonstrated that the fraction preceding and that following the one containing 3 : 4-benzpyrene were carcinogenic to rodents though free from spec...
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Article
Carcinogenic Activity and O-Alkylation
IT is well known that many natural products, flower pigments, essential oils, alkaloids, etc., contain methoxy-groups, and that some of these compounds show remarkable biological activities, for example, colch...
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Article
Hepatotoxic Activity of Semi-Synthetic Analogues of Pyrrolizidine Alkaloids
MANY of the natural pyrrolizidine alkaloids isolated from various plants are not only acutely hepatotoxic, but are also able to produce subacute and chronic liver lesions in rats when given in an appropriate s...
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Article
Carcinogenic Action of Diazomethane and of Nitroso-N-methyl Urethane
THE transformation of inactive or slightly active compounds into effective carcinogens by O-methylation has been discussed previously1, and it was suggested that endogenous carcinogens may possibly be formed by a...
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Article
Interaction of the Carcinogenic N-Methyl-Nitrosourethane with Sulphydryl Groups
IN a preliminary communication I recently reported the production of lung adenoma in mice and squamous lung carcinoma in a rat, which was exposed to gaseous diazomethane. Among other rats given N-methyl-N-nitroso...
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Article
Photodecomposition of N-alkyl-N-nitroso-urethanes
IN the course of investigations of the carcinogenic action of N-methyl-N-nitroso-urethane (NMU)1 it was observed that dilute solutions of this compound in aqueous ethanol, when left in direct sunshine, became dec...
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Article
Induction of Tumours of the Stomach in Rats and Mice by N-nitroso-N-alkylurethanes
THE induction of squamous carcinoma of the stomach and, of the oesophagus in the rat by N-nitroso-N-methyl-urethane (NMU)1 and by some other nitrosamines2 has been reported. Squamous tumours of the stomach have b...
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Article
Induction of Intestinal Tumours by N-Ethyl-N-nitrosourethane
INTESTINAL tumours, though very rare in laboratory rodents, have been induced by several types of carcinogenic agents, including polycyclic aromatic hydrocarbons, 4-dimethylaminostilbene, 2-acetyl-aminofluoren...
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Article
Carcinogenic Activity of N-Methyl-N-nitroso-N′-nitroguanidine
N-METHYL-N-NITROSOURETHANE (MNU) (I) and its ethyl homologue have been found to be effective carcinogens, which can induce stomach, oesophageal, intestinal and lung tumours with one or a few doses1–6. As urethane...
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Article
Effects of N-Methyl-N-nitrosourethane on Cells in Tissue Culture
A COMMUNICATION on the morphological conversion of cells in vitro by N-nitrosomethylurea by Sanders and Burford1 prompts me to report similar experiments performed about 5 years ago in which the related and very ...
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Article
Carcinogens in Chinese Incense Smoke
CONSIDERATION of the high incidence of naso-pharyngeal cancer among the Chinese1 led us to search for carcinogenic constituents in condensates from burning Chinese incense. Using thin-layer arid column chromatogr...
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Article
Selenium-75 in the Harderian Glands and Brown Fat of Rats given Sodium Selenite labelled with Selenium-75
SELENIUM is an essential micro-element for animal tissues, which can, however, cause acute and chronic poisoning and even liver tumours when its concentration in food exceeds a few p.p.m. Its specific role is ...
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Article
Carcinogenic and Chronic Effects of 4,4′-Diaminodiphenylmethane, an Epoxyresin Hardener
4,4′-DIAMINODIPHENYLMBTHANE (DDM) (I) has been in use in the rubber industry as an epoxyresin hardener and such like on an ever increasing scale for more than 20 years. This compound belongs to the class of ar...
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Article
Carcinogenic Action of Elaiomycin in Rats
SEVERAL natural products of plant or microbial origin have been discovered in the past 20 yr that have proved carcinogenic in experimental animals1. These products include certain pyrrolizidine alkaloids, luteosk...
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Article
Hepatotoxic Activity of Retrorsine, Senkirkine and Hydroxysenkirkine in Newborn Rats, and the Role of Epoxides in Carcinogenesis by Pyrrolizidine Alkaloids and Aflatoxins
NEWBORN rats have proved strikingly more susceptible than weanlings to the hepatotoxic action of a single dose of the hepatocarcinogen retrorsine, and also to senkirkine and hydroxysenkirkine (cyclic diesters ...
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Article
Herbal Medicines to Avoid
IN East Africa, certain rare tumours, oesophageal, nasopharyngeal, liver, Burkitt lymphomas and the like, are concentrated in distinct localized pockets1. The reason for this and the aetiology of these tumours ar...
