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Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Syrian golden hamsters were given intratracheal instillations of glass fibres with or without benzo[a]pyrene suspended in saline, once a fortnight for 52 weeks. The experiment was terminated at week 85. 'Silicotic granulomas' consisting of tightly packed, iron-positive macrophages filled with glass fibres and surrounded by a layer of alveolar epithelial cells were the predominant pulmonary lesion. No mesotheliomas or other tumours of the respiratory tract were observed in hamsters treated with glass fibres alone. There was no indication that glass fibres enhanced the development of respiratory tract tumours induced by benzo[a]pyrene. In hamsters similarly exposed to crocidolite fibres with or without benzo[a]pyrene no mesotheliomas or other respiratory tract tumours were observed either. An explanation for the absence of pulmonary tumours might be that repeated administration of fibres over a period of 52 weeks entails an acute pulmonary reaction after each administration with the implication that the fibres cannot settle down well enough to be able to induce tumours. Another possible explanation is the relatively short duration of the experimental period.
Carcinogenesis 1985 Oct
PMID:Pulmonary response of hamsters to fibrous glass: chronic effects of repeated intratracheal instillation with or without benzo[a]pyrene. 404 77

Kinetics of the content of nonheme iron-sulphur-containing (iron-sulphur) proteins, free radicals of electron-transport mitochondrial system, as well as of microsome terminal oxidase cytochrome P-450 is studied in the liver of rats at early stages of carcinogenesis and in the process of tumour growth induced by intratracheal administration of various benz(a)pyrene doses. It is found that the content of iron-sulphur proteins increases after the first administration, then it falls against a background of higher concentration of free radicals. A degree of pronounced changes in the content of the studied iron-sulphur proteins correlates with carcinogen dose. The cytochrome P-450 content is lowered for almost the whole period of carcinogen administration. In later periods animals with morphologically determinable pretumour changes exhibit a much higher content of iron-sulphur proteins, somewhat increased concentration of free radicals and a tendency to an increased level of cytochrome P-450. The appearance and growth of malignant tumours is followed by a considerable decrease in the content of iron-sulphur proteins and cytochrome P-450. On the basis of the results obtained it is supposed that the changes in the content of iron-sulphur proteins in the rat liver is the earliest and most pronounced reaction which depends on the benz(a)pyrene dose and may be of prognostic significance.
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PMID:[Kinetics of metallo-enzymatic paramagnetic centers and free radicals in the rat liver in lung carcinogenesis]. 609 96

Rat acinar cells in the azaserine-induced hyperplastic nodules or adenomas in the siderotic pancreas produced by repeated iron injections were found to be resistant to iron accumulation. These iron-resistant acinar cell lesions coincided rather well with the lesions having markedly decreased activity of gamma-glutamyl transpeptidase. These properties of the acinar cells could be useful for the identification of early lesions in pancreatic carcinogenesis.
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PMID:Exclusion of cellular iron and reduced gamma-glutamyl transpeptidase activity in rat pancreas acinar cell hyperplastic nodules and adenomas induced by azaserine. 613 91

Some metals are essential oligo-elements for man. However, if the body load of these same metal derivatives becomes excessive they may be responsible for deleterious effects, particularly cytotoxic ones. Metals are divided into four categories: potent carcinogens; presumptive carcinogens with a documented cocarcinogenic effect; ascertained cocarcinogens; metals with no demonstrated carcinogenic or cocarcinogenic effect. The most common tumors induced by metals are those of the lung. Arsenic induces cancer of the lung and skin, beryllium may induce lung cancer, the effects of cobalt are dubious, cadmium can induce cancer of the lung and, above all, prostate, the role of iron is uncertain, hexavalent chrome may induce cancer of the lung and nasal fossae, nickel is responsible for cancer of lung and nasal fossae. Our understanding of metal carcinogenesis is clearly insufficient and more experimental research and epidemiologic studies addressing this subject are needed.
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PMID:[Carcinogenic effect of metals]. 631 79

The effect of iron deficiency on oral carcinogenesis was investigated in 30 young adult male Charles River white rats. In 15 animals, prior to the start of carcinogen treatment, iron deficiency anaemia was produced and subsequently maintained by a combination of low iron diet (12 mg Fe2+ kg-1 diet) and repeated venesection. Fifteen control animals were fed the same diet supplemented with iron to approximately 140 mg FE2+ kg-1 diet. All animals were treated with the carcinogen 0.5% 4-Nitroquinoline-N-oxide in propylene glycol which was painted on the palate 3 times weekly. Animals were killed when tumours were grossly evident. The mean haemoglobin levels at the start of carcinogen applications were 10.1 g dl-1 in the anaemic group and 14.1 g dl-1 in the control group, and at the time of killing were 8.2 g dl-1 in anaemic animals and 13.8 g dl-1 in controls. The incidence of animals developing squamous cell carcinomas was similar in both groups, but tumour development was significantly earlier in iron-deficient animals (mean 183 days) compared to controls (mean 229 days). Iron-deficient animals showed a significantly greater incidence of tongue tumours and control animals showed a significantly greater incidence of palatal tumours.
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PMID:The effect of iron deficiency on experimental oral carcinogenesis in the rat. 640 24

One of the possible reasons for peculiar features of the tumour cell energetics is discussed. Regular variations in the iron-sulphur protein content in the mitochondrial electron transport chains were shown in models of chemical and hormonal carcinogenesis. A decrease in the content of these proteins in the tumoural tissue is found at early stages of malignant growth against a background of higher concentration of free radicals. Irreversible nature of an iron-sulphur protein decrease was observed in the liver and adrenals of tumour-bearing animals both under development of hormonal genesis tumours and at various stages of chemical carcinogenesis. Coming from the results obtained it is suggested that disturbances in the state of iron-sulphur proteins affect the oxidation phosphorylation efficiency and that modification of compensatory mechanism results in the glycolysis activation, which is a characteristic feature of the tumour cell energetics.
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PMID:[Iron-sulfur centers and free radicals of the electron transfer chains of mitochondria in chemical and hormonal carcinogenesis]. 641 81

Seventeen nickel compounds were administered to Fischer-344 rats (N = 270) by intrarenal injection (7 mg Ni/rat); the compounds included nickel sulfides, selenides, arsenides, oxide, antimonide, telluride, titanate, ferronickel alloy and metallic nickel dust. Erythrocytosis, as defined by peak hematocrit values that averaged greater than 55% during 1-4 months post-injection, occurred in nine of 17 Ni-treated groups (NiS2, beta NiS, alpha Ni3S2, Ni4FeS4, NiSe, Ni3Se2, NiAsS, NiO, Ni dust). Renal cancers (N = 23) developed within 2 years post-injection in nine of 17 Ni-treated groups (NiS2, beta NiS, alpha Ni3S2, Ni4FeS4, NiSe, Ni3Se2, NiAsS, NiAs, NiFe alloy). The renal cancers included eight fibrosarcomas, five mesangial cell sarcomas, two renal cell carcinomas, two carcinosarcomas, two leiomyosarcomas, two undifferentiated sarcomas, one rhabdomyosarcoma and one nephroblastoma. No erythrocytosis or renal cancers occurred in control rats (N = 97) in three groups treated with the vehicles or metallic iron dust. Rank correlation (p less than 0.0001) was observed between the incidences of erythrocytosis and renal cancers in the 17 Ni-treated groups. Rank correlation (p less than 0.001) was observed between the present incidences of renal cancers and the sarcoma incidences previously reported following intramuscular administration of the 17 nickel compounds to Fischer-344 rats (14 mg Ni/rat). The incidences of renal cancer were not correlated with the mass-fractions of nickel in the 17 compounds, the dissolution half-times of the compounds in rat serum or renal cytosol, or the phagocytic indices of the compounds in rat peritoneal macrophages.
Carcinogenesis 1984 Nov
PMID:Association between erythrocytosis and renal cancers in rats following intrarenal injection of nickel compounds. 648 75

A total of 40 metals are reviewed and summarized to give a general perspective on the metal's two major effects, relevant to medicine and psychiatry in man. These two effects are metal excess (poisoning) and deficiency. These metals are grouped arbitrarily into six categories; (a) The heavy metals, (b) the essential and questionable essential trace elements, (c) the macrominerals, (d) the alkali metals, (e) elements used as therapeutic agents, and (f) miscellaneous elements. The heavy metals are invariably toxic and could be lethal, and no deficiency state has yet been described in man, although arsenic has been postulated to be essential. The essential trace elements are vital to a number of vital physiological and biochemical functions, and newer essential trace elements are to be identified in the future. The recent findings suggest vanadium excess may aggravate the affective symptoms in bipolar affective disorder; selenium may inhibit certain carcinogenesis such as oesophageal cancer; and silicon may inhibit atheromatous formation in the aorta. There is also some suggestion that certain allergic syndromes may be correlated with very low levels of iron, copper, manganese. The study of elements will undoubtedly expand the understanding of disease processes in medicine and psychiatry.
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PMID:A synopsis on metals in medicine and psychiatry. 652 32

The enhancement of hepatocarcinogenesis by butylated hydroxytoluene (BHT) in comparison with that by phenobarbital (PB) was studied by quantifying their effects on N-2-fluorenylacetamide (FAA)-induced preneoplastic and neoplastic rat-liver lesions. Hepatocellular altered foci identified by iron exclusion and gamma-glutamyltranspeptidase (GGT) activity were induced by feeding 0.02% FAA for 8 wk. Subsequently, BHT was fed at concentrations of 300, 1000, 3000 or 6000 ppm for up to 22 wk after cessation of FAA exposure; PB was fed at concentrations of 316 or 500 ppm for comparison. The lower doses of BHT (300, 1000 and 3000 ppm) did not exert a significant effect on either foci development or the final yield of neoplasms. At 6000 ppm, BHT increased the number of foci, the area occupied by GGT-positive preneoplastic and neoplastic lesions and the neoplasm incidence, as did 316 and 500 ppm PB. Comparison of the effects of BHT and PB at equimolar concentrations revealed that BHT was a much weaker enhancer of liver carcinogenesis. Apparently, the effective dose range of BHT as an enhancer is rather restricted. On the basis of available evidence that BHT is nongenotoxic and exerts epigenetic effects, we conclude that BHT is a weak promoter of liver carcinogenesis.
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PMID:Enhancing effect of butylated hydroxytoluene on the development of liver altered foci and neoplasms induced by N-2-fluorenylacetamide in rats. 653 37

The early stages of N-2-fluorenylacetamide [(2-FAA) CAS: 59-96-3]-induced liver carcinogenesis in inbred F344 male and female rats and the effect of gonadectomy on liver carcinogen biotransformation capability and hepatocarcinogenesis were studied. Feeding of 2-FAA induced more altered hepatocellular foci characterized by exclusion of cellular iron and gamma-glutamyl-transferase activity in male rats than in female rats. At 6-22 weeks after cessation of carcinogen exposure, only males developed liver neoplastic nodules. Liver cytochrome P450, aryl hydrocarbon hydroxylase, and uridine-5'-diphosphateglucuronosyltransferase activity toward p-nitrophenol, but not phenolphthalein, were greater in males than in females. Gonadectomy of males reduced the activities that were greater than in females, whereas none was significantly altered by gonadectomy of females. Gonadectomy of male rats prior to 2-FAA feeding suppressed the induction of both altered foci and neoplastic nodules, whereas in female rats gonadectomy prior to 2-FAA feeding enhanced the induction of foci. Gonadectomy of males after administration of 2-FAA slightly enhanced the persistence of foci at 6 and 12 weeks after removal of carcinogen, but it did not affect their persistence by 22 weeks post carcinogen or the incidence of neoplastic nodules. However, only the males that were gonadectomized after receiving 2-FAA developed hepatocellular carcinomas at 22 weeks. Gonadectomy of females after receiving 2-FAA did not affect the persistence of foci, and no liver neoplasms developed. Thus gonadectomy of male rats, which reduced liver carcinogen metabolism, when done before carcinogen feeding had the greatest effect on hepatocarcinogenesis.
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PMID:Early stages of N-2-fluorenylacetamide-induced hepatocarcinogenesis in male and female rats and effect of gonadectomy on liver neoplastic conversion and neoplastic development. 658 22


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