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Biomedical subjects

J E Rice

Publications and source records attributed to J E Rice.

At least 37 records · Page 2Linked to original sources
PubMed1992

Chemotaxis of polymorphonuclear leukocytes in whole blood in the 'sparse-pore' polycarbonate (Nuclepore) membrane/Boyden chamber assay.

Chemotaxis of polymorphonuclear leukocytes (PMN) in 100%, 50% and 25% whole blood as well as in separated preparations were compared using both N-formyl peptide and interleukin-8 as chemoattractants and Boyden-type chambers with 'sparse-pore' polycarbonate (Nucleopore, California) membranes. In addition, attachment, spreading and 'drop-off' of cells from the 'sparse-pore' membrane were documented. In whole blood, fewer PMN attached to the membrane, but these showed greater chemotactic activity and exhibited more spreading and more 'drop-off' than separated PMN. Despite these differences, the 'sparse-pore' polycarbonate membrane system may be used to assay chemotaxis with whole blood as the source of PMN.

Cell Adhesion↗
PubMed1992

Sequences directing dihydrolipoamide dehydrogenase (E3) binding are located on the 2-oxoglutarate dehydrogenase (E1) component of the mammalian 2-oxoglutarate dehydrogenase multienzyme complex.

Sequences located in the N-terminal region of the high M(r) 2-oxoglutarate dehydrogenase (E1) enzyme of the mammalian 2-oxoglutarate dehydrogenase multienzyme complex (OGDC) exhibit significant similarity with corresponding sequences from the lipoyl domains of the dihydrolipoamide acetyltransferase (E2) and protein X components of eukaryotic pyruvate dehydrogenase complexes (PDCs). Two additional features of this region of E1 resemble lipoyl domains: (i) it is readily released by trypsin, generating a small N-terminal peptide with an apparent M(r) value of 10,000 and a large stable 100,000 M(r) fragment (E1') and (ii) it is highly immunogenic, inducing the bulk of the antibody response to intact E1. This 'lipoyl-like' domain lacks a functional lipoamide group. Selective but extensive degradation of E1 with proteinase Arg C or specific conversion of E1 to E1' with trypsin both cause loss of overall OGDC function although the E1' fragment retains full catalytic activity. Removal of this small N-terminal peptide promotes the dissociation of dihydrolipoamide dehydrogenase (E3) from the E2 core assembly and also affects the stability of E1 interaction. Thus, structural roles which are mediated by a specific gene product, protein X in PDC and possibly also the E2 subunit, are performed by similar structural elements located on the E1 enzyme of the OGDC.

Amino Acid Sequence↗
PubMed1990

Fluorine probes for investigating the mechanism of activation of indeno[1,2,3-cd]pyrene to a tumorigenic agent.

Indeno[1,2,3-cd]pyrene (IP) is a non-alternant polycyclic aromatic hydrocarbon that has tumor-initiating activity on mouse skin and is carcinogenic in newborn mice and in rat lungs. Previous studies have shown that 8- and 9-hydroxyIP and IP-1,2-diol are major metabolites formed in vivo in mouse skin. 8-HydroxyIP-1,2-diol and 9-hydroxyIP-1,2-diol are also observed as in vivo metabolites of IP. Although 8-hydroxyIP had marginal tumor-initiating activity on mouse skin, IP-1,2-diol and its epoxide precursor, IP-1,2-oxide, had similar tumorigenic activity as IP. In the present study fluorine probes have been employed to investigate the contribution of metabolic activation at the 1,2 and 7-10 positions of IP. At a total initiating dose of 4.0 mumol, 2-fluoroIP induced skin tumors in 76% of the treated animals with an average of 3.9 tumors/mouse. At the same dose, IP induced a 72% incidence of tumor-bearing mice with 2.1 tumors/mouse. In contrast, 8,9-difluoroIP elicited a tumorigenic response in 40% of the treated animals with 0.6 tumors/animal. Five mice from each experimental group were killed at the conclusion of the initiation phase of the bioassay and DNA was isolated from the treated areas of skin. 32P-Postlabeling analysis of the hydrolyzed DNA indicated that IP forms one major detectable DNA adduct that migrates close to the origin. This adduct is absent in mice treated with 8,9-difluoroIP. In contrast, 2-fluoroIP forms one major adduct spot with different retention behavior as compared with the adduct formed from IP. DNA from mice treated topically with IP-1,2-diol and IP-1,2-oxide was subjected to 32P-postlabeling analysis. IP-1,2-diol forms one major DNA adduct spot with mobility similar to that observed for the IP-DNA adduct. IP-1,2-oxide displayed an intense pattern of DNA adducts centered around the location of the IP-DNA adduct. No adducts were detected which had mobility similar to that formed from 2-fluoroIP. These results are consistent with IP undergoing metabolic activation at positions 7-10 either alone or in conjunction with dihydrodiol formation at the 1,2 position.

Animals↗
PubMed1989

The effect of cholera toxin on the inhibition of vasopressin-stimulated inositol phospholipid hydrolysis is a cyclic AMP-mediated event at the level of receptor binding.

Incubation of L6 skeletal myoblasts for 16 h with cholera toxin but not with pertussis toxin, led to the inhibition of inositol phosphate generation induced by subsequent exposure to vasopressin. The effects of the toxin on inositol lipid metabolism were accompanied by the total ADP-ribosylation of the available cholera-toxin substrates within the cells. Immunological analysis demonstrated that the two polypeptides modified in vivo by cholera toxin were different forms of Gs alpha (alpha subunit of Gs). No novel cholera-toxin substrate(s) were detected. The cholera-toxin-mediated inhibition of vasopressin-stimulated inositol phosphate generation could be mimicked by both forskolin and dibutyryl cyclic AMP, but not by the separated subunits of the toxin. Receptor-binding studies demonstrated that the inhibition of agonist-stimulated inositol phosphate generation was accompanied by a decrease in cell-surface vasopressin-binding sites, with no effect on the affinity of these for the hormone. We suggest that the effect of cholera toxin and agents which increase intracellular cyclic AMP on vasopressin-stimulated inositol lipid hydrolysis is an effect on receptor number, and that there is no requirement to postulate a role for a novel G-protein, which is a substrate for cholera toxin, in the regulation of inositol phospholipid metabolism.

Adenosine Diphosphate↗
PubMed1988

The influence of fluoranthene on the metabolism and DNA binding of benzo[a]pyrene in vivo in mouse skin.

The effect of the cocarcinogen fluoranthene on the DNA binding and metabolism of [3H]benzo[a]pyrene (B[a]P) in vivo in mouse skin has been investigated. In the presence of fluoranthene the level of B[a]]P-DNA binding was increased at each of the time intervals examined (4, 8, 24 and 48 h) with enhancements ranging from 76% at 4 h to 36% at 48 h. The ratio of anti-7,8,-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE)-DNA adducts/syn-BPDE-DNA adducts was also increased in the presence of fluoranthene. This increase was greatest at 8 h (44%) but by 48 h the ratio was identical in the presence and absence of fluoranthene. The observed increase in anti-BPDE-DNA adducts/syn-BPDE-DNA adducts did not parallel increases in B[a]P-DNA binding suggesting that alteration of the anti-BPDE/syn-BPDE ratio is not a major contributing factor to the cocarcinogenic activity of fluoranthene. The influence of fluoranthene on the metabolism of B[a]P in vivo in mouse skin was also investigated. Fluoranthene was found to have little or no effect on the formation of ethyl acetate extractable metabolites of B[a]P in mouse skin. Specifically, there was no increase in the amount of B[a]P-7,8-diol in the presence of fluoranthene. Fluoranthene also had little or no effect on the levels of beta-glucuronide or sulfate conjugates of B[a]P metabolites formed in vivo in mouse skin. These studies suggest that the effect of fluoranthene is being expressed at some point after B[a]P has been activated to an ultimate carcinogen.

Animals↗
PubMed1988

Comparative tumor-initiating activity of methylene-bridged and bay-region methylated derivatives of benz[a]anthracene and chrysene.

Polycyclic aromatic hydrocarbons (PAHs) with a methylene-bridge spanning the bay region are often detected in higher concentrations in the environment than PAHs which have a bay-region methyl substituent. The tumor-initiating activity of methylene-bridged bay-region derivatives of chrysene and benz[a]anthracene was evaluated on the skin of female CD-1 mice. 4,5-Methylenechrysene elicited twice as many tumors as chrysene at each of the doses tested. At total initiation doses of 1.5, 0.5 and 0.15 mumol/mouse 4,5-methylenechrysene gave rise to 8.5, 6.8 and 1.1 tumors/animal respectively. There was a 100% incidence of tumor-bearing mice at the two higher doses and a 65% incidence at the lowest dose. This methylene-bridged hydrocarbon was less tumorigenic than 5-methylchrysene at each dose tested. Animals treated with 1,12-methylenebenz[a]anthracene developed 7.6, 4.9 and 1.6 tumors/animal at total initiating doses of 4.0, 2.0 and 0.5 mumol/mouse. The incidence of tumor-bearing mice was 90% at the higher doses and 75% at the lowest dose tested. 12-Methylbenz[a]anthracene was more tumorigenic than the methylene-bridged derivative at each dose. The keto-derivative of 1,12-methylenebenz[a]anthracene did not display significant (P greater than 0.05) tumor-initiating activity at these dose levels. Results from these bioassays indicate that methylene-bridged bay-region derivatives of chrysene and benz[a]anthracene contribute to the overall genotoxicity of environmentally occurring PAHs.

Animals↗
PubMed1988

Metabolism and mutagenic activity of benzo[k]fluoranthene and 3-, 8- and 9-fluorobenzo[k]fluoranthene.

The metabolism of 3-, 8- and 9-fluorobenzo[k]fluoranthene (B[k]F) relative to B[k]F was investigated. The major metabolites of B[k]F formed in vitro using rat liver S-9 metabolism systems were 8,9-dihydro-8,9-dihydroxyB[k]F, the 2,3-quinone of B[k]F and 3-, 8- and 9-hydroxyB[k]F. Fluorine substitution within the structure of B[k]F substantially altered the types of metabolites formed in vitro. The most pronounced effect was observed with 9-fluoroB[k]F. In contrast to B[k]F, the 8,9-dihydro-8,9-dihydroxy-, 9-hydroxy- and 10,11-dihydro-10,11-dihydroxy derivatives were not detected as metabolites of 9-fluoroB[k]F. However, either the 2,3- or 4,5-dihydrodiol of 9-fluoroB[k]F was detected. In the case of 8-fluoroB[k]F, neither the 8- nor 11-hydroxy- derivatives were detected. The principle dihydrodiols formed from 8-fluoroB[k]F were the 10,11-dihydrodiol and either the 2,3-or 4,5-dihydrodiol. The pattern of metabolites formed with 3-fluoroB[k]F was similar to that observed with B[k]F with the exception that neither the 3- nor 4-hydroxy derivatives were formed. Mass spectral data indicated that fluoro substitution is not lost to any appreciable extent during the metabolism of 3-, 8- and 9-fluoroB[k]F. The mutagenic activity of these B[k]F fluoro derivatives along with B[k]F, 2,3-dihydro-2,3-dihydroxyB[k]F, the 2,3-quinone of B[k]F and 8,9-dihydro-8,9-dihydroxyB[k]F were evaluated in Salmonella typhimurium TA100 in the presence of rat liver S-9 metabolism systems. 3-FluoroB[k]F was more mutagenic than B[k]F, while both 8- and 9-fluoroB[k]F were less active. While the 2,3-dihydrodiol and 2,3-quinone were weakly active, the 8,9-dihydrodiol had similar mutagenic potency to B[k]F.

Animals↗
PubMed1987

Identification of tumorigenic metabolites of benzo[j]fluoranthene formed in vivo in mouse skin.

The metabolism of benzo[j]fluoranthene (BjF) in vivo in mouse skin was investigated. trans-4,5-Dihydro-4,5-dihydroxybenzo[j]fluoranthene (BjF-4,5-diol) and trans-9,10-dihydro-9,10-dihydroxybenzo[j]fluoranthene (BjF-9,10-diol) have been identified as major metabolites. In addition, 4- and 10-hydroxybenzo[j]fluoranthene and benzo[j]fluoranthen-4,5-dione have been tentatively identified among the metabolites formed in vivo in mouse skin. The enantiomeric purity of the metabolic dihydrodiols of BjF as formed in vivo in mouse skin was determined. The major enantiomer of BjF-4,5-diol was present in 57-62% enantiomeric excess while that of BjF-9,10-diol was present in 66-71% enantiomeric excess. In each case the later-eluting enantiomer on chiral stationary-phase high performance liquid chromatography predominated. The tumor-initiating activity of trans-2,3-dihydro-2,3-dihydroxybenzo[j]fluoranthene (BjF-2,3-diol), BjF-4,5-diol, BjF-9,10-diol, and BjF was evaluated on the skin of female CD-1 mice. As a total initiation dose of 3 mumol/mouse BjF-4,5-diol resulted in a 100% incidence of tumor-bearing mice with 5.0 tumors/mouse. In comparison, BjF-9,10-diol elicited a 60% incidence of tumor-bearing mice with 1.7 tumors/mouse, while BjF-2,3-diol was inactive. At the same dose, BjF gave rise to a 90% incidence of tumor-bearing mice with 7.8 tumors/mouse. At a 1-mumol dose, BjF-4,5-diol induced a 78% incidence of tumor-bearing mice with 4.3 tumors/mouse while BjF gave rise to a 70% tumor incidence with 3.4 tumors/mouse while BjF gave rise to a 70% tumor incidence with 3.4 tumors/mouse. These studies indicate that while BjF-9,10-diol could contribute to the overall tumorigenic activity of BjF in mouse skin, BjF-4,5-diol is a more potent tumor initiator in the target tissue.

Animals↗
PubMed1987

Identification of metabolites of benzo[j]fluoranthene formed in vitro in rat liver homogenate.

The metabolites of benzo[j]fluoranthene (BjF) as formed in vitro using the 9000 X g supernatant from Aroclor-pretreated rats have been identified. Two dihydrodiols, trans-4,5-dihydro-4,5-dihydroxyBjF and trans-9,10-dihydro-9,10-dihydroxyBjF have been identified as major metabolites by comparison of their spectral and chromatographic properties with those of pure synthetic standards. There was no evidence that any of the isomeric 2,3-dihydrodiol was formed as a metabolite of BjF under these incubation conditions. Neither of the metabolic dihydrodiols of BjF were formed with a high degree of stereoselectivity. The enantiomeric purity of the 4,5-dihydrodiol was 20% while that of the 9,10-dihydrodiol was 46%. At least four phenols were detected among the metabolites of BjF. These were identified as 3-, 4-, 6- and 10-hydroxyBjF based upon comparison of their UV spectra and HPLC retention times with those of synthetic reference standards. BjF-4,5-dione was also identified as a metabolite under these incubation conditions.

Animals↗
PubMed1987

Tumorigenic activity of non-alternant polynuclear aromatic hydrocarbons in newborn mice.

The tumorigenic activity of benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene, and indeno-[1,2,3-cd]pyrene was evaluated in newborn CD-1 mice. The total doses of these non-alternant polycyclic aromatic hydrocarbons employed in this study ranged from 0.5 to 2.1 mumol per mouse. The results of this assay indicate that both benzo[b]fluoranthene and benzo[j]fluoranthene exhibit significant tumorigenic activity. In contrast to these results, neither benzo[k]fluoranthene nor indeno[1,2,3-cd]pyrene were tumorigenic under these assay conditions.

Animals↗
PubMed1987

32P-postlabeling analysis of DNA adducts from non-alternant PAH using thin-layer and high performance liquid chromatography.

DNA adduct formation in vivo in mouse skin following a single topical application of benzo[a]fluoranthene (BbF), benzo[j]fluoranthene (BjF), benzo[k]fluoranthene (BkF), or indeno[1,2,3-cd]pyrene (IP) was investigated in female CD-1 mice using 32P-postlabeling analysis. Distinct adduct profiles were detected for each of the non-alternant hydrocarbons examined. Two adducts, one major and one minor, were detected using polyethyleneiminecellulose (PEI-cellulose) thin-layer chromatography (TLC) for BbF and BjF while a single major adduct was detected for BkF and IP. The relative extent of binding to mouse skin DNA was in the order BbF greater than BjF greater than BkF greater than IP. 32P-Postlabeled DNA adducts separated by PEI-cellulose TLC were further analyzed by high performance liquid chromatography (HPLC). A single radioactive peak was detected for 32P-labeled DNA adducts of BjF and BkF. Three general areas of radioactivity were detected when 32P-labeled DNA adducts of BbF were separated on HPLC.

Animals↗
PubMed1987

Methylated derivatives of pyrene and fluorene: evaluation of genotoxicity in the hepatocyte/DNA repair test and tumorigenic activity in newborn mice.

The genotoxicity of 1-methylpyrene, 1,6-dimethylpyrene, 1-methylfluorene, 9-methylfluorene, and 1,9-dimethylfluorene was evaluated in the hepatocyte primary culture/DNA repair test, and the tumorigenic potency of these compounds was tested by bioassay in newborn mice. With the exception of 1-methylfluorene, all of these methylated polycyclic aromatic hydrocarbons are known mutagens in Salmonella typhimurium. Both 1-methylpyrene and 1,6-dimethylpyrene induced unscheduled DNA synthesis in rat hepatocytes. However, only 1-methylpyrene was tumorigenic when administered to newborn male mice. None of the methylated fluorenes assayed in the hepatocyte primary culture/DNA repair test induced unscheduled DNA synthesis. While 1,9-dimethylfluorene exhibited weak tumorigenic activity when administered by subcutaneous injection to newborn mice, 1-methylfluorene and 9-methylfluorene were inactive.

Animals↗
PubMed1986

Tumor-initiating activity of major in vivo metabolites of indeno[1,2,3-cd]pyrene on mouse skin.

Indeno[1,2,3-cd]pyrene is a ubiquitous environmental pollutant which is active as a tumor initiator and complete carcinogen on mouse skin and is carcinogenic in rat lung. The major metabolites of indeno[1,2,3-cd]pyrene as formed in vivo in mouse skin have been identified. 8-Hydroxyindeno[1,2,3-cd]pyrene is the most abundant metabolite identified. 9-Hydroxyindeno[1,2,3-cd]pyrene and trans-1,2-dihydro-1,2-dihydroxyindeno[1,2,3-cd]pyrene are also major in vivo metabolites in mouse skin. Several minor metabolites were also identified. Among these are trans-1,2-dihydro-1,2,8-trihydroxyindeno[1,2,3-cd]pyrene, trans-1,2-dihydro-1,2,9-trihydroxyindeno[1,2,3-cd]pyrene, indeno[1,2,3-cd]pyrene-1,2-dione, and 10-hydroxyindeno[1,2,3-cd]pyrene. The tumor-initiating activity of several of the major in vivo metabolites of indeno[1,2,3-cd]pyrene has been investigated on mouse skin. Trans-1,2-dihydro-1,2-dihydroxyindeno[1,2,3-cd]pyrene and 1,2-dihydro-1,2-epoxyindeno[1,2,3-cd]pyrene both produced an 80% incidence of tumor-bearing mice at a total initiating dose of 1.0 mg. The activity of this K-region dihydrodiol and K-region oxide was, however, less than that of the parent hydrocarbon. These data suggest that 1,2-dihydro-1,2-epoxyindeno[1,2,3-cd]pyrene, which is an ultimate mutagenic metabolite of indeno[1,2,3-cd]pyrene, is not the ultimate tumorigenic metabolite on mouse skin. 8-Hydroxyindeno[1,2,3-cd]pyrene, which is mutagenic when assayed in the presence of a microsomal activation system, exhibited only weak tumor-initiating activity. These results indicate that the principal metabolic activation pathways associated with the mutagenic activity of indeno[1,2,3-cd]pyrene are not related to its tumor-initiating activity on mouse skin.

Animals↗
PubMed1985

Studies on the mutagenicity and tumor-initiating activity of methylated fluorenes.

Several methylated analogs of fluorene were evaluated as mutagens in Salmonella typhimurium TA98 and TA100 in the presence and absence of microsomal activation. Among the methylated derivatives of fluorene assayed were 9-methylfluorene, 2-fluoro- and 2,7-difluoro-9-methylfluorene, 1,9-, 2,9-, 3,9- and 4,9-dimethylfluorene, 2,3,9-trimethylfluorene and 2,7,9-trimethylfluorene. Mutagenic activity was observed for several of these fluorene derivatives in the presence of rat liver homogenate. The data support a previous observation that a single methyl substituent in the 9-position of fluorene is associated with mutagenic activity within this series of compounds. Substitution with fluorine at both the 2- and 7-positions of 9-methylfluorene was not associated with a loss of mutagenic activity as evidenced by the similar mutagenic activity of 2,7-difluoro-9-methylfluorene and 9-methylfluorene. However, 2,7,9-trimethylfluorene was not mutagenic under these assay conditions. 9-Methylfluorene, 1,9-, 2,9-, 3,9- and 4,9-dimethylfluorene and 2,3,9-trimethylfluorene were active as mutagens in the presence of rat liver homogenate, but were inactive as tumor initiators when assayed on mouse skin.

Animals↗
PubMed1985

Methylene-bridged bay region chrysene and phenanthrene derivatives and their keto-analogs: mutagenicity in Salmonella typhimurium and tumor-initiating activity on mouse skin.

A series of methylene-bridged and keto-bridged bay region derivatives of chrysene and phenanthrene were prepared and evaluated for mutagenic activity in Salmonella typhimurium TA100 and for tumor-initiating activity on CD-1 mouse skin. The compounds included in this series were 4H-cyclopenta[def]phenanthrene, 4H-cyclopenta[def]phenanthrene-4-one, 1-methyl-4H-cyclopenta[def]phenanthrene, 1-methyl-4H-cyclopenta[def] phenanthren-4-one, 4H-cyclopenta[def] chrysene, and 4H-cyclopenta[def] chrysen-4-one. Among these compounds only 4H-cyclopenta[def]phenanthrene and 1-methyl-4H-cyclopenta[def]phenanthren-4-one were not significantly mutagenic when assayed with metabolic activation using Aroclor-induced rat liver homogenate. None of the compounds assayed were active without metabolic activation. 4H-Cyclopenta[def]chrysene was the most tumorigenic of the methylene-bridged bay region PAH tested on mouse skin. At a dose of 1.0 mg this compound resulted in 100% of the animals bearing papillomas with 5.63 papillomas/animal. 4H-Cyclopenta[def]chrysen-4-one and 1-methyl-4H-cyclopenta[def]phenanthrene displayed weak tumorigenic activity at a total initiating dose of 1.0 mg.

Animals↗
PubMed1985

Tumor-initiating activity, mutagenicity, and metabolism of methylated anthracenes.

Specific methylated derivatives of anthracene are mutagenic in S. typhimurium and have tumor-initiating activity on mouse skin. In this study, the mutagenic activities of 1-, 2-, and 9-methylanthracene, 2,9- and 9,10-dimethylanthracene, 2,9,-10-trimethylanthracene, 2,3,9,10-tetramethylanthracene, and the photo-oxide of 9,10-dimethylanthracene were determined in S. typhimurium TA98 and TA100. The relative tumor-initiating activities of these compounds were also evaluated. These bioassays indicate that increased mutagenic potency and tumor-initiating activity are associated with the presence of a methyl substituent at both the 9- and 10- position of anthracene. Metabolism studies suggest that the biological activity of specific methylated anthracenes may be related to the formation of a simple epoxide adjacent to a peri-methyl substituent.

Anthracenes↗