Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BENZOPYRENES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMedDate not supplied

[Metabolism of air polluting organic compounds in plants].

The review discusses the date in the plant uptake and conversion of gaseous C1--C5 alkanes, hydroaromatic hydrocarbon--cyclohexane, aromatic mononuclear hadrocarbons--benzene and toluene, polycyclic carcinogenic hydrocarbon -- benzopyrene, monobasic alcohols - isopropyl, isobutyl, amyl, hexyl and octyl alcohols, aldehydes - formaldehyde and acetaldehyde, ketone - acetone, monocarboxylic acids -- formic, acetic, butyric, caproic and acetoacetic acids, phenols - hydroxybenzene and alpha-naphthol. The paper outlines pathways of their detoxication in plants and biochemical foundations of air purification from organic pollutants.

Air Pollutants↗
PubMed1978

Altered growth properties of Chinese hamster cells exposed to 1-methylguanine and 7-methylguanine.

Primary Chinese hamster embryo cell cultures generally yield cell lines with a finite lifetime in culture. However, if early-passage cells are exposed chronically to either of two normal degradation products of transfer RNA, 1-methylguanine or 7-methylguanine, they are converted to continuous lines with altered growth characteristics and morphology. The continuous cell lines have saturation densities 2- to 10-fold higher than did finite control cultures, and some have the ability to grow in soft agar. Certain cultures have the general appearance of fibroblasts while others are more epithelial-like. Quantitative and qualitative alterations in the transfer RNA methyltransferases are early markers for neoplastic transformation in vivo and in vitro. Transfer RNA methyltransferase activity in the continuous lines is elevated compared to that of finite Chinese hamster cells. Neoplastic transformation has been demonstrated for a 1-methylguanine-derived line, and both 1-methylguanine- and 7-methylguanine-treated cell lines exhibit characteristics similar to those of Chinese hamster cells transformed with the carcinogen 3,4-benzopyrene or the DNA tumor virus SV40.

Animals↗
PubMedDate not supplied

Two types of cells in the normal, atypical and carcinomatous squamous epithelium of the cervix. I. Light microscopic and autoradiographic study in mice.

The occurrence of two morphologically distinct cell types in the cervical epithelium of mice is reported. One of the two cell types had a large nucleus with a limited amount of cytoplasm. Cells with these characteristics were called cells with "lucid nuclei." Such cells were found in film-coated autoradiographic specimens that had been fixed in Carnoy's solution; they were readily observed by altering the quality of the light illuminating the preparations. Micrometric determinations confirmed that cells with "lucid nuclei" were larger than cells with "nonlucid nuclei." Both cell types were demonstrated to synthesize DNA and RNA precursors. The proportion of cells with "lucid nuclei" was increased in 3.4-benzopyrene-induced atypias; the highest values were reached in squamous invasive carcinoma. The causes of the significant increase in cells with "lucid nuclei" during cervical carcinogenesis in the mouse are unclear.

Animals↗
PubMed1982

[In vitro effect of culture fluids from neoplastic tissues on platelet aggregation. II. Experimental tumors].

We have investigated the effects on platelet function of culture media from 2 sublines of a benzopyrene-induced murine sarcoma (mFS6). Platelet aggregation was investigated according to Born's method. The cell line with greater "in vivo" invasiveness showed higher aggregating activity and higher increase on ADP-induced aggregation; these effects were inhibited by the preincubation of platelets with Aspirin (0,1 mM). These results suggest the role of platelets in metastasis formation; the possibility to inhibit pharmacologically the interactions between platelets and tumour cells could have important implications from both speculative and practical viewpoints.

Adenosine Diphosphate↗
PubMedDate not supplied

[Silicosis and bronchial cancer (author's transl)].

1. At world level, silicosis does not predispose to bronchial cancer. But from region to region, the relationship silicosis-cancer varies and depends on factors other than silica. 2. It has not been proved that silica is cancerigen in laboratory animal. 3. Subjects exposed to silica can also be exposed in other circumstances to known carcerigen agents (ionizing radiations, iron oxides, arsenic, exhaust gases of explosion engins). In Switzerland, it is possible that miners in galeries could breath low concentrations of radon and benzopyrene. But it is very difficult to know to what extent these potential risks are involved. 4. Bronchial carcinoma in silicotic patients does not own any characteristics. It is quite similar to that found in the remainder of the population. On the other hand, its diagnosis and treatment are more difficult because of the presence of silicosis. 5. The fortuitous association of silicosis and bronchial cancer is due to overlapping of the profiles of both diseases. The increasing life span of the silicotic patient and the high frequency of bronchial cancer explain why this association is not more exceptional.

Animals↗
PubMed1980

Microsomal mixed-function oxidase and activities of some related enzymes in hyperplastic nodules induced by long-term griseofulvin administration in mouse liver.

Hepatic hyperplastic nodules induced in mice by long-term griseofulvin administration were examined for selected microsomal activities and responses to enzyme inducers. Despite a decrease in microsomal cytochrome P-450 in hyperplastic nodules, aminopyrine N-demethylase was at control levels. Benzopyrene hydroxylase activity was slightly lower in microsomes derived from hyperplastic nodules than in those of control liver. Reduced nicotinamide adenine dinucleotide-cytochrome b5 reductase was at control level, but reduced nicotinamide adenine dinucleotide- and reduced nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome c reductases and the NADPH-ferricyanide reductase were increased. NADPH-supported lipid peroxidation was lower in microsomes from hyperplastic nodules than in those from control liver, whereas microsomal stearoyl coenzyme A desaturase activity was almost doubled in the nodules. NADPH-cytochrome c reductases isolated and semipurified from hyperplastic nodule and from control liver microsomes showed almost identical affinity for NADPH. Microsomal enzymes of hyperplastic nodules responded readily to phenobarbital induction, but sodium dodecyl sulfate-polyacrylamide gel electrophoresis disclosed differences in the polypeptide patterns in the molecular weight range from 47,000 to 54,000 between microsomes derived from hyperplastic nodules and control livers.

Animals↗
PubMed1995

KR-30450, a newly synthesized benzopyran derivative, activates the cardiac ATP-sensitive K+ channel.

KR-30450 (2-(2"(1",3"-dioxolone)-2-methyl-4-(2'-oxo-1'-pyrrollidinyl) -6- nitro-2H-1-benzopyren) is a newly synthesized benzopyran derivative. We examined the effect of KR-30450 on the action potential duration of isolated rat papillary muscle and on the ATP-sensitive K+ channel (KATP) activity in single rat ventricular myocytes with 3 M KCl-filled conventional microelectrode and patch clamp techniques. KR-30450 (10(-7) approximately 10(-5) M) reduced the action potential duration in a concentration-dependent manner and this was inhibited by 3 microM glibenclamide, suggesting that KATP was involved. In cell-attached patches, KR-30450 (10(-5) M) in the pipette activated the KATP which was closed by 3 microM glibenclamide. In inside-out patches, the effects of KR-30450 on KATP activity were examined before and after run-down of the channel. Before run-down, KR-30450 increased the KATP activity only in the presence of ATP and shifted the [ATP]i-KATP activity relationship to the right. After run-down, KR-30450 did not affect the KATP activity either in the presence or absence of 3 mM UDP, but increased the UDP-induced KATP activity in the presence of 1 mM ATP-gamma-S. From these results, we conclude that KR-30450 antagonizes the inhibitory effect of ATP on the KATP in a competitive manner. These effects of KR-30450 are similar to those of ER-001533 and HOE-234, but different from those of pinacidil and lemakalim.

Action Potentials↗
PubMed1994

Electrophysiological studies of nerve and muscle in comparative neoplasia.

The purpose of this study was to test the effect of tumor on neuromuscular function in rats and to compare the neoplastic neuro-myopathy in patients with the animal model. In the I experimental part were performed: EMG examination, motor nerve conduction velocity and membrane resting potential defining, test with repetitive supramaximal stimulation and measurement of the muscle weight on rats with transplanted epithelioma Guérin (EG) as well as with benzopyrene induced fibrosarcoma (Sa). II Clinical part was carried out in patients with neoplasma using routine electrophysiological methods. The results obtained in the I part indicate the neurogenic atrophy of the muscle, progressing with tumor development. The pathological signs were much more expressed in E.G. group than in Sa group. In the II part it was found the decrease of sensory nerve's excitability and of EMG surface. Concluding the transplantable tumor (EG) influence in rats neuromyopathy with the destruction of the whole motor unit. They are strict relations between the findings observed in E.G. rats and those reported in patients with neoplastic disease.

Action Potentials↗
PubMed1993

[Malignant tumors or the small intestine. Review of the literature and report of a clinical case].

The authors present one case of patients with adenocarcinoma of the small bowel. Primary malignant tumors of the small intestine are uncommon neoplasms accounting for 1-2 per cent of all gastrointestinal malignancies. Patients are usually seen late in the course of their illness when curative therapy is unlikely. The rarity of these neoplasms explains in part why the early signs and symptoms frequently go unrecognized and is undoubtedly a major factor contributing to their poor prognosis. Despite a fourfold greater length and a nearly tenfold greater mucosal surface area, the incidence of adenocarcinoma of the small intestine is about a fortieth that of the colon. This relative immunity of the small bowel to the development of the malignant tumors is unexplainable. Several theories have been suggested and include the following: a) the rapid transit time of the small intestine may reduce its exposure to dietary carcinogens; b) the relative sterility of the small intestine compared with the colon may lessen the formation of carcinogenic substances by the action of bacteria on components of bile or other substances within the intestinal lumen; c) certain mucosal enzymes such as benzopyrene hydroxylase that detoxify potential carcinogens are present in higher concentrations in the small intestine than in the colon; d) immunoglobulin A which is found in high concentrations in the small bowel, may protect it against carcinogenic viruses. Interestingly, patients deficient in IgA and those receiving immunosuppressive therapy have been found to have a higher incidence of small intestinal cancer. Adenocarcinoma is the most common primary malignant small bowel neoplasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1996

Ontogenic development of drug-metabolizing enzymes in male chicken liver.

The ontogenic study of the hepatic biotransformation enzymes revealed the early development of both oxidative and conjugative enzymes in male chickens ranging in age from 3 to 12 weeks. Although the rate of microsomal cytochrome P450 reactions progressively increased during the first 9 weeks, it decreased thereafter. Furthermore, the proteins revealed by the antibodies to anti-cytochrome P450 1A2, 2B4, 2C7, and 3A4 appeared to be constitutively expressed. Hepatic monooxygenases were characterized by different developmental patterns. The demethylase activities increased progressively up to 9 weeks, then they declined, in 12 weeks reaching the activity level observed in 3-week-old chickens. In contrast, alkoxyresorufin O-dealkylases and benzopyrene hydroxylase activities continued to increase with age. Significant variability was noted for aniline hydroxylase. Among conjugation enzymes, UDP-glucuronyltransferase towards p-nitrophenol and isoniazid N-acetyltransferase activities increased with the age of the fowl, but with different profiles. Concerning glutathione S-transferase accepting 1-chloro-2,4-dinitrobenzene or 1,2-dichloro-4-nitrobenzene, the chickens aged from 3 to 9 weeks were less well developed in this enzyme than 12-week-old ones.

Age Factors↗
PubMed1997

[The significance of nutrition in primary prevention of cancer].

The complex process of carcinogenesis is mainly due to environmental factors and therefore preventable. Diet may account for about 35% of cancer cases; risk factors and protective factors are discussed. Accordingly, obesity is associated with an increased risk of endometrial and postmenopausal breast cancers. Less clear is the relationship with colorectal and prostate cancer. The observed inverse association of body weight with lung cancer risk is most probably confounded by smoking habits and/or the effect of preclinical cancer. The risk factor fat has been studied mainly in relation to colorectal, breast and prostate cancer; the results are controversial. More consistent are the associations between (red) meat consumption and risk of colorectal and prostate cancer. Alcohol is a risk factor for tumors of the upper gastrointestinal tract, the hepatocellular carcinoma and the (distal) colorectal cancer. Even small amounts of alcohol seem to increase the risk of breast cancer. Residues, contaminants, mycotoxins and additives like benzopyrene, nitrosamine(s), and aflatoxine are associated with a smaller risk of cancer than "overnutrition". High intake of fruit and vegetables is related to a reduced risk of lung cancer and cancer of the upper gastrointestinal tract. What the specific chemicals in fruits and vegetables are that are responsible for this association are still unclear. Despite only weak associations between dietary factors and cancer risk, for potential protective effects it is recommendable to increase the consumption of fruit and vegetables, to avoid obesity, to reduce the intake of fat, meat and alcohol and to avoid cured, pickled, smoked, and mouldy food.

Alcohol Drinking↗
PubMed1998

Drug metabolism in in vitro organotypic and cellular models of mammalian central nervous system: activities of membrane-bound epoxide hydrolase and NADPH-cytochrome P-450 (c) reductase.

The membrane-bound form of epoxide hydrolase and NADPH-cytochrome P-450 (c) reductase are two important enzymes involved in the bioactivation/bioinactivation balance of cerebral tissue. In vivo, the developmental profiles and regional localizations of these two enzymes were investigated in the rat. The regional distribution study showed that they are ubiquitously present among the major brain structures. Both enzyme activities were present in the brain prior to birth, and hence tissue from early developmental stages is suitable to develop in vitro cellular or organotypic models for toxicity studies involving these metabolic pathways. Because various neurotoxicological effects can be dependent on spatio-temporally regulated cell-cell interactions, we aimed to employ organotypic tissue cultures in which the cytoarchitecture was well preserved. In such cultures, the temporal expression profiles of epoxide hydrolase and NADPH cytochrome(c) P-450 reductase reflected the in vivo situation. The technically less demanding pure neuronal and glial cell cultures were also investigated. Detoxification of benzopyrene-4,5-epoxide and superoxide production arising from the reductive metabolism of various drugs were determined in all three systems. The results indicate that though organotypic culture is a good model for the metabolic pathways studied, less complicated single cell cultures can also represent appropriate model systems, providing that the expression of the enzymes involved has been first established in these systems. NADPH-cytochrome P-450 reductase-dependent metabolism is active in both neuronal and glial cells, whereas the detoxification of reactive epoxides occurs mainly in glia.

Animals↗
PubMed1976

Comparison of the hydroxylation of zoxazolamine and benzo[a]pyrene in human placenta: effect of cigarette smoking.

The in vitro hydroxylation of zoxazolamine was compared with the hydroxylation of benzo[a]pyrene (BP) in full-term placentas from 11 nonsmokers and from 13 women who smoked cigarettes during pregnancy. Cigarette smoking increased the average zoxazolamine and benzo[a]pyrene hydroxylase activities 13- and 39-fold, respectively. A 59-fold range in benzo[a]pyrene hydroxylase activity and a 28-fold range in zoxazolamine hydroxylase activity were found in the placentas of cigarette smokers. A plot of these two enzyme activities showed that zoxazolamine hydroxylase activity was highly correlated, with benzo[a]pyrene hydroxylase activity in the 24 placentas studied (r = 0.98; p less than 0.001). A strong correlation between the above enzymatic activities was also found in 8 placentas which had been stored for 2 yr at -20 degrees C (r = 0.95; p less than 0.001). The results suggest that benzo[a]pyrene and zoxazolamine are metabolized in the human placenta by the same enzyme or by different systems that are under the same regulatory control.

Benzopyrene Hydroxylase↗
PubMed1977

Comparative metabolism of benzo[a]pyrene and drugs in human liver.

The oxidative metabolism of antipyrine, hexobarbital, coumarin, zoxazolamine, 7-ethoxycoumarin, and the chemical carcinogen benzo[a]pyrene (BP) was studied in 32 adult human livers obtained at autopsy. When enzyme activity for one substrate was plotted against enzyme activity for a second substrate for each of the 32 livers, statistically significant correlations were found between the rates of metabolism of BP and the rates of metabolism of each of the other five drug substrates. The degree of correlation was dependent upon the substrate pair that was studied. Highly significant statistical correlations (p less than 0.001) for monooxygenase activities among the different livers were observed for BP with antipyrine (r = 0.85), antipyrine with zoxazolamine (r = 0.82), antipyrine with hexobarbital (r = 0.79), zoxazolamine with 7-ethoxycoumarin (r = 0.75), antipyrine with coumarin ( r= 0.72), zoxazolamine with coumarin (r = 0.72), BP with hexobarbital (r = 0.72), hexobarbital with coumarin (r = 0.71), BP with zoxazolamine (r = 0.69), hexobarbital with zoxazolamine (r = 0.64), coumarin with 7-ethoxycoumarin (r = 0.61), and BP with coumarin (r = 0.57). Less significant correlations were obtained for BP with 7-ethoxycoumarin (r = 0.35; p = 0.05). It is not known whether the relationships between the metabolism of the several substrates described here for autopsy livers would also occur with fresh livers. The lack of a perfect correlation for any of the substrate pairs suggests the presence in human liver of multiple monooxygenase enzyme systems for the metabolism of benzo[a]pyrene and the five other substrates studied, as well as heterogeneity in their distribution among the 32 livers that were examined. The approach described in the present report may have significance in the study of the comparative metabolism of drugs, chemical carcinogens, and other environmental pollutants by human tissues and may help us find predictor drugs that will be useful for evaluating the drug- and carcinogen-metabolizing capacity of different individuals in the human population.

Adolescent↗