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Biomedical subjects

R O Mumma

Publications and source records attributed to R O Mumma.

At least 19 recordsLinked to original sources
PubMed1991

Inhibition of lipoxygenase and prostaglandin endoperoxide synthase by anacardic acids.

C22:1 omega 5-anacardic acid was found to be a good inhibitor of both potato lipoxygenase and ovine prostaglandin endoperoxide synthase with approximate IC50's of 6 and 27 microM, respectively. Very similar inhibition was seen with the crude exudate, rich in omega 5-anacardic acids, from glandular trichomes of an arthropod-resistant strain of geranium, Pelargonium xhortorum. The saturated anacardic acid (C22:0 sat), abundant in the trichome exudate of susceptible strains, was nearly as inhibitory toward both prostaglandin endoperoxide synthase and lipoxygenase as the omega 5-unsaturated compound. However, the dimethyl derivative of C22:1 omega 5-anacardic acid was a poor inhibitor of prostaglandin endoperoxide synthase and caused only moderate (32%) inhibition of lipoxygenase even at 135 microM. The possible role of prostaglandin endoperoxide synthase and lipoxygenase inhibition in the enhanced pest resistance of geraniums which produce the omega 5-AnAs is discussed.

Aspirin↗
PubMed1988

In vitro activation assays with hepatic S9 preparation from wild and laboratory reared woodchucks in the Salmonella mutagenicity test.

The Salmonella mutagenicity assay was utilized to compare hepatic S9 fractions derived from wild and laboratory reared woodchucks (Marmota monax). Two promutagens, 7,12-dimethylbenz[a]anthracence (DMBA) and 2-amino-fluorene (AF) were tested at 5 concentrations with the tester strains TA98 and TA100, against 2 levels of S9 fraction. AF produced similar number of revertants with the S9 fraction from wild and laboratory-reared animals. DMBA produced 2-4 times more revertant colonies at 50 microliter S9/plate with wild woodchuck S9 than with S9 from the laboratory-reared animals with both tester strains. It was concluded that natural inducers in the wild woodchuck diet may have contributed to the increased reversion frequency over laboratory reared woodchucks. Dose-response parameters for the activation of DMBA by S9 fraction from woodchucks and rats were compared with TA100. Woodchuck S9 had 3-40 more revertants/nmol and a 100-fold lower threshold of response than S9 from Aroclor 1254-induced rats.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

Mutagenic potency of some conjugated nitroaromatic compounds and its relationship to structure.

The mutagenicities of 12 conjugated non-fused nitroaromatic compounds and 1 amino analogue were determined in strains TA100 and TA98 of Salmonella typhimurium. Reversions by p-nitroaromatics increased in the order of the acetophenone, benzaldehyde, styrene, chalcone, cinnamic acid and stilbene indicating the importance for mutagenic potency of extended conjugation to the p-nitrophenyl substituent. Highest mutagenicity was found with alpha-substituted 4-nitrostyryl derivatives of which the phenyl derivative (31 revertants per nmole in TA100) was the most active. Generally, the TA100 strain was more sensitive than TA98 to these mutagens and S9 treatment was unnecessary for activity, although 4-nitrochalcone required S9 activation. Para-nitro isomers of the cinnamic acids and chalcones were much more active than the corresponding ortho and meta isomers. The 4-aminocinnamic acid analogue was inactive suggesting that complete reduction in Salmonella of 4-nitrocinnamic acid to an active amino derivative is not response for the high mutagenicity of the former. Mutagenicity of these p-nitrostyryl compounds may be explained by the covalent interaction of the electrophilic benzylic carbon with Salmonella DNA.

Mutagenicity Tests↗
PubMed1987

Mutagenicity of chloroaniline/lignin metabolites in the Salmonella/microsome assay.

Chloroanilines are constituents of many agrochemicals and have been found to be metabolized to succinic acid conjugates, e.g., succinamides and succinimides. The mutagenic potential of five chloroanilines and their succinamides and succinimide derivatives have been tested with two strains of Salmonella typhimurium (TA98 and TA100) with and without rat hepatic microsomal fraction. None of the compounds produced a dose response effect with a two-fold increase in revertants indicating that these compounds are not mutagens or promutagens in these assays.

Aniline Compounds↗
PubMed1987

Residues and mutagenicity of captan applied to apple trees and potential human exposure.

The fungicide captan (cis-N-((trichloromethyl)thio) 4-cyclo-hexene-1,2-dicarboximide) was applied at the rate of 2.4 g/l to apple trees (c.v. Golden Delicious) individually or as part of a standard treatment program where it was applied eight times during the growing season together with several pesticides. Leaf samples (100 discs of 2.2 cm diameter) were collected from treated and control trees before treatment and at 0, 1, 3, 7, 14, 28, 56, 90 and 112 days after treatment. Fruit samples were taken at mid-season (56 days) and at harvest (112 days). The objective of this study was to determine the captan residue and mutagenicity of leaf and fruit extracts to ascertain the potential health hazard to agricultural workers in these orchards. Surface residues were extracted from leaves and fruits with methylene chloride. These extracts were subsequently analyzed for captan by gas-liquid chromatography (GLC) utilizing an electron-capture detector, and for mutagenicity with two strains (TA98 and TA100) of Salmonella typhimurium, with and without microsomal enzyme activation. Positive mutagenic effects were observed with strain TA100 at 0-14 days post spray, even with extracts from one leaf disc's surface (3.8 cm2) of the single treatment. Captan residues in these samples indicated a decline from 9.3 micrograms/cm2 at 0 days to 0.80 micrograms/cm2 at 14 days and a trace after 112 days. With the standard treatment, in which captan was incorporated eight times in the program starting at the 7-day interval, leaf extracts showed mutagenic activity at 7, 14, 28 and 90 days. Captan residues at these intervals were 11.4, 5.0, 4.1 and 3.4 micrograms/cm2, respectively. Fruit sample extracts of the standard spray were mutagenic to the tester strains TA100 and TA98 both at mid-season and at harvest. Residues of captan on fruits declined from 10.4 micrograms/cm2 at mid-season to 1.1 micrograms/cm2 at harvest. No mutagenic activity was detected with extracts from fruit samples from the single captan application.

Captan↗
PubMed1986

Structure-mutagenicity relationships of chalcones and their oxides in the Salmonella assay.

31 p-monosubstituted chalcones (E-1, 3-diphenylpropene-1-one) and the corresponding oxides (E-1-benzoyl-2-phenyloxirane) were tested for mutagenic activity on two strains of Salmonella typhimurium (TA98 and TA100) with and without rat liver microsomal and cytosolic enzymes. Highest mutagenicity (3.0 revertants/nmole in either strain) was seen with the 4-nitrochalcone, especially after S9 activation. Epoxidation, in general, increased the mutagenic activity of the respective chalcone. Benzoyl (4') substituted chalcones and their oxides with an electron-withdrawing substituent (e.g., nitro, fluoro) usually had higher activity than their phenyl (4) substituted counterparts, whereas the converse was the case with electron-donating substituents (e.g., acetamido, methoxy). Further multiple factorial analysis revealed that increasing hydrophilicity as indicated by the Hansch pi parameter, and resonance electronic contributions were more important than other factors including steric terms in explaining the mutagenicity of these compounds. Mutagenic effects of some chalcone oxides, particularly the 4-methoxy derivative, were markedly decreased by S9 treatment. The consequence of the weak-to-moderate mutagenicity of these compounds to dietary intake of hydroxylated and methoxylated chalcones is discussed.

Animals↗
PubMed1986

Evaluation of beta-naphthoxyacetic acid for mutagenic activity in the Salmonella/mammalian microsome assay.

Beta-naphthoxyacetic acid (BNOA) is used as a plant growth regulator on tomatoes and strawberries. It is the active ingredient in Blossom-Set and Berry-Set, two plant hormone sprays for fruit-set. The mutagenic activity of BNOA was evaluated in four strains of Salmonella typhimurium (TA97, TA98, TA100 and TA1535) in the presence and absence of liver microsomal and cytosolic enzymes derived from Aroclor induced rats. BNOA did not produce any significant increase (p less than 0.05) in the reversion of any of the four tester strains in the standard plate incorporation assay. Results of the agar overlay toxicity tests indicates that the chemical shows toxic effects at concentrations above 500 micrograms/plate. It was concluded that under the conditions of these tests, BNOA did not exhibit any mutagenic activity.

Animals↗
PubMed1986

Screening pesticides for their ability to damage bacterial DNA.

Twenty-six pesticides and pesticide degradation products were screened (125 micrograms - 2000 micrograms) for their ability to induce unrepairable damage to bacterial DNA. Three repair test systems were utilized in this study, the Salmonella typhimurium (TA1538/TA1978), the E. coli K-12 (Pol A1+/Pol1-) and the E. coli WP2 (WP2, WP2uvrA, WP67, CM611 and CM571). Aldicarb (1000 micrograms), benomyl (250 micrograms), 2-aminobenzimidazole (2000 micrograms), captan (125 micrograms), fenazalor (500 micrograms), 5,6-dichloro-2-trifluoromethylbenzimidazole (NC-2983) (250 micrograms), isothymol (250 micrograms), maleic hydrazide (1000 micrograms), pentachloronitrobenzene (1000 micrograms) were DNA-damaging to one or more bacterial test systems. Isothymol and NC-2983 affected all three test systems. Chlorinated hydrocarbon insecticides, some being recognized as carcinogens, did not produce a zone of inhibition in any of the tester strains possibly due to their poor solubility and diffusion in the agar overlay. It was concluded that these tests can be performed along with bacterial reversion tests to complement each other as short-term screening tests for potential carcinogens and mutagens.

DNA Damage↗
PubMed1986

Toxic and protective constituents in pet foods.

An analytical survey of mutagens, nitrosamines, polychlorinated biphenyls, toxic elements, and gamma-emission, as well as the toxicologically protective constituents zinc, selenium, and vitamin C, in 48 pet foods was conducted. Aside from high concentrations of fluoride and iodide in some samples and the expectedly higher concentrations of mercury and selenium in certain cat foods containing fish, the samples were notably free of the other toxic constituents. Direct-acting and promutagens and nitrosamines were not detectable in any of the samples. gamma-Emission was very low in all of the foods. Polychlorinated biphenyls were only detected in one cat food.

Animal Feed↗
PubMed1985

Comparative mutagenicity tests in the Salmonella/microsome assay with rat and woodchuck S9 preparations.

The Salmonella mutagenicity assay was utilized to compare the hepatic S9 fractions from untreated and 3-methylcholanthrene (MC) induced woodchucks with Aroclor 1254 induced rats. Three known promutagens, benzo[a]pyrene (BP), 7,12-dimethylbenz[a]anthracene (DMBA), and 2-aminofluorene (AF) were tested at 5 concentrations with the strain TA100 against 3 levels of S9 fraction. Both woodchuck S9 fractions were as effective as the rat S9 in activating BP and both were more effective than the rat S9 in activating DMBA. Untreated woodchuck S9 was also as effective as rat S9 in activating AF. The protein content of the S9 fraction did not differ significantly between rats and woodchucks, but the P-450 content of the rat S9 was approximately 3.5 times that of woodchuck.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1985

Mutagenicity tests with gallic and tannic acid in the Salmonella/mammalian microsome assay.

Gallic acid, tannic acid mixture and a purified fraction of tannic acid were evaluated for possible mutagenic activity in three strains of Salmonella typhimurium, TA98, TA100, and TA1535. These chemicals were not mutagenic either before or after activation with rat and woodchuck microsomal and cytosolic enzymes. However, tannic acid mixture and tannic acid fraction both gave a significantly (p = 0.05) dose-related reduction in the number of the revertant colonies, compared to the normal spontaneous revertants with no apparent toxic effects in the background lawn. With an agar diffusion assay, the chemicals exhibited toxic effects at 5000 micrograms/disc.

Animals↗
PubMed1984

Testing of 2,4,5-T-amino acid conjugates for mutagenic activity in Salmonella typhimurium strains.

Since amino acid conjugates are plant metabolites of the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 5 amino acid conjugates (aspartic acid, glutamic acid, leucine, methionine and tryptophan) of 2,4,5-T were tested for possible mutagenic activity utilizing 5 strains of Salmonella typhimurium (TA97, TA98, TA100, TA1535 and TA1538) with and without rat-liver microsomal and cytosolic enzymes. These compounds did not cause any significant increase in reversions when compared with controls in the presence or absence of the activating system. Further, linear regression analysis showed no significant (p less than 0.05) dose-response relationships. Thus, it was concluded that the tested amino acid conjugates of 2,4,5-T are not mutagens or promutagens in these assays.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed1984

Evaluation of chlordimeform and degradation products for mutagenic and DNA-damaging activity in Salmonella typhimurium and Escherichia coli.

The mutagenic activity of chlordimeform and two of its breakdown products, 4-chloro-o-toludine and 4-chloro-N-formyl-o-toluidine were determined with five histidine dependent strains of Salmonella typhimurium (TA1535, TA1537, TA1538, TA98, TA100) and five tryptophan dependent strains of E. coli WP2 (WP2, WP2uvrA, WP67, CM611, CM571) with and without rat liver microsomal enzymes. 4-chloro-o-toluidine increased the number of the reversions of the S. typhimurium strain TA1535 more than two fold over spontaneous at the concentration of 400 micrograms/plate. The results of the DNA repair tests in the Salmonella TA1538/TA1978 and E. coli multirepair deficient systems showed that both breakdown products were active in inducing damage not repaired in at least one repair deficient strain while chlordimeform itself was inactive.

Amidines↗
PubMed1984

Genotoxicity of methyl parathion in short-term bacterial test systems.

Genotoxicity of the insecticide methyl parathion was investigated in Salmonella typhimurium and Escherichia coli bacterial test systems for the detection of back mutations and DNA-damage. Methyl parathion was mutagenic to S. typhimurium strain TA100 after activation with rat liver microsomal and cytosolic enzymes. In DNA repair tests, methyl parathion was effective in inducing damage to the S. typhimurium strain TA1538 which lack excision repair compared to the strain TA1978 which is proficient in excision repair mechanisms. Normal laboratory light conditions had no effect on the mutagenicity tests, however, exposure of methyl parathion in the petri dish containing the tester strain TA100 and rat liver microsomal and cytosolic enzymes reduced the mutagenic activity and increased the toxic effects of methyl parathion.

DNA Repair↗
PubMed1982

Advances in pesticide metabolite identification through the use of plant tissue cultures.

Plant tissue cultures are powerful tools for metabolism studies. Culture conditions can be selected which mimic conditions of whole plants or conditions can be employed to mass-produce selected metabolites such as aglycons or conjugates. Culture variables that affect metabolism are medium composition, age of tissue cultures, concentration of test chemical, and the source of plant tissue. The type of culture, such as suspension cultures, callus tissue cultures, differentiated tissue or organ cultures will also influence the type of metabolites obtained. Ease of standardizing conditions makes tissue culture suitable to comparatively examine metabolism in different plant species and strains and in different plant parts such as tissues derived from leaves and roots. Recent advances with plant tissue cultures involve studies of the mechanism of action or selectivity of growth regulators and herbicides, and the use of resistant strains to investigate mechanisms of biological detoxification.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1982

Gas-liquid chromatographic determination of fenvalerate insecticide residues in processed apple products and by-products.

Apples from trees treated in the field at 2-week intervals (9 foliar applications) with the synthetic pyrethroid insecticide fenvalerate (cyano(3-phenoxyphenyl) methyl 4-chloro-alpha-(1-methylethyl)-benzeneacetate) were processed into apple sauce, juice, pomace, and peels plus cores. Gas-liquid chromatographic analysis of the commodities for fenvalerate showed the sauce and juice to be essentially residue-free, the whole apples to contain about 0.4 ppm, and the pomace and peels plus cores to contain about 2 and 1.5 ppm, respectively. Agreement among 5 laboratories using modifications of the same basic method was good.

Beverages↗
PubMed1977

Effects of ascorbic acid and its 2-sulfate on rabbit aortic intimal thickening.

Effects of intravenously injected L-ascorbic acid or L=ascorbic acid 2-sulfate on aortic intimal thickening were examined histologically, qualitatively, and quantitatively in the upper, middle and lower thoracic aortic positions of cholesterol-induced atherosclerotic rabbits. A means of evaluating the degree of pathology of the aortic positions was developed employing five descriptive statistics of intimal thickening. Both L-ascorbic acid and L-ascorbic acid 2-sulfate inhibited intimal thickening. The most significant reductions were observed in the upper thoracic aorta.

Adrenal Glands↗