101
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Juchau MR. Species and organ differences in the biotransformation of chemical carcinogens. BASIC LIFE SCIENCES 1983; 24:273-281. [PMID: 6860267 DOI: 10.1007/978-1-4684-4400-1_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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102
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Majesky MW, Yang HY, Benditt EP, Juchau MR. Carcinogenesis and atherogenesis: differences in monooxygenase inducibility and bioactivation of benzo[a]pyrene in aortic and hepatic tissues of atherosclerosis-susceptible versus resistant pigeons. Carcinogenesis 1983; 4:647-52. [PMID: 6305525 DOI: 10.1093/carcin/4.6.647] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Atherosclerosis-susceptible White Carneau (WC-2) pigeons were compared with atherosclerosis-resistant Show Racer (SR-39) pigeons in terms of hepatic and aortic biotransformation and bioactivation of benzo[a]pyrene (B[a]P). Following pretreatment of the two strains with 3-methylcholanthrene (MC, 40 mg/kg), WC-2 hepatic 9000 X g supernatant fractions (S-9) exhibited consistently greater increases in the production of specific B[a]P metabolites when compared with uninduced controls than did the corresponding SR-39 preparations. Analyses of organic solvent-extractable metabolites with h.p.l.c. revealed that inducer pretreatment resulted in significantly greater increases (18- versus 7-fold) in the generation of B[a]P-7,8-dihydrodiol by WC-2 versus SR-39 hepatic S-9. Similar differences in inducibility were found for most other metabolites appearing in the h.p.l.c. profiles. Hepatic monooxygenase systems were induced in both strains following treatment of pigeons with a mixture of polychlorinated biphenyls (Aroclor 1254, 500 mg/kg); WC-2 birds again demonstrated greater responsiveness. Bioactivation of B[a]P to mutagenic (but not cytotoxic) products by hepatic S-9 was more effective in preparations from MC-pretreated WC-2 versus SR-39 pigeons when assessed with Salmonella typhimurium tester strains. Aortic homogenates from MC-pretreated pigeons displayed even greater inducibility differences than were observed with hepatic preparations. Inducer-mediated increases in the formation of B[a]P-7,8- and B[a]P-9,10-dihydrodiols were approximately 10- and 12-fold greater in WC-2 than SR-39 aortic preparations, respectively. The results document marked differences in biotransformation and bioactivation of carcinogenic hydrocarbons by atherosclerosis-susceptible and resistant pigeons and are reminiscent of the metabolic differences observed in carcinogenesis-susceptible and resistant strains of mice. It is suggested that these pigeon strains might offer a promising system in which to further study the role of target tissue biotransformation in the atherogenic actions of polynuclear aromatic hydrocarbons.
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103
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Namkung MJ, Chao ST, Juchau MR. Placental mono-oxygenation: characteristics and partial purification of a hematin-activated human placental mono-oxygenase. Drug Metab Dispos 1983; 11:10-14. [PMID: 6132788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Human placental mono-oxygenase activities were markedly increased after additions of micromolar quantities of hematin to reaction vessels. The magnitude of the increases diminished with increasing (induced) levels of hematin-independent activity. The activating effect of hematin could be observed in unbroken cell preparations, in whole homogenates, and in various subcellular fractions. Highest hematin-dependent activity was measured in microsomal fractions of placental homogenates. With benzo(a)pyrene as substrate, response to the stimulatory effect of hematin in human placental preparations was not as profound as that observed in monkey or rabbit placentas but was more marked than the responses observed in placental preparations from rats or mice. Hematin-activated mono-oxygenase activity present in washed microsomal fractions of human placental homogenates could be solubilized with detergents, the most effective of which was Triton N-101. The solubilized activity also could be partially purified by polyethylene glycol fractionation. Attempts to further purify, however, resulted in loss of activity. All results were consistent with the hypothesis that the effect of hematin is mediated via reconstitution of hematin-free apocytochrome(s) P-450.
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104
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Namkung MJ, Faustman-Watts E, Juchau MR. Hematin-mediated increases of benzo(a)pyrene mono-oxygenation in maternal, fetal and placental tissues of inducible and non-inducible mouse strains. DEVELOPMENTAL PHARMACOLOGY AND THERAPEUTICS 1983; 6:199-206. [PMID: 6305612 DOI: 10.1159/000457295] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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105
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Greenaway JC, Shepard TH, Fantel AG, Juchau MR. Sodium salicylate teratogenicity in vitro. TERATOLOGY 1982; 26:167-71. [PMID: 7157193 DOI: 10.1002/tera.1420260209] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Rat embryos were exposed to sodium salicylate in vitro at concentrations comparable to those used to produce terata in vivo. Embryos treated with 400, 600, or 800 micrograms Na salicylate/ml were compared with embryos treated with an equimolar concentration of NaCl. When compared to growth of the controls, a significant dose-dependent decrease in growth parameters was observed. The incidence of abnormal embryos characterized by generalized swelling (particularly in the area of the rhombencephalon) was also dose dependent. This study demonstrates the teratogenicity of salicylate in the rat independent of maternal factors.
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106
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Greenaway JC, Fantel AG, Shepard TH, Juchau MR. The in vitro teratogenicity of cyclophosphamide in rat embryos. TERATOLOGY 1982; 25:335-43. [PMID: 7112435 DOI: 10.1002/tera.1420250310] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
When Day 10 rat embryos were grown in culture containing cyclophosphamide, an hepatic microsomal fraction (S-9), and cofactors for monooxygenation, they developed characteristic malformations. When a fixed volume of CP was added to cultures the number of malformed embryos was increased and their growth decreased dependent upon the S-9 concentration. In one group of experiments S-9 was prepared from animals which had been pretreated with either phenobarbital (PB) or 3-methylcholanthrene (MCA). All embryos cultured with CP by S-9 from animals pretreated with polychlorinated biphenyls (Aroclor 1254) microliter/ml) was used. No malformations were seen under the same conditions when MCA-induced S-9 (0.25-12.5 microliter/ml) was substituted. The teratogenic activation of CP by S-9 from animals pretreated with polychlorinated biphenyls (Aroclor 1254) was inhibited in vitro by the addition of either metyrapone or carbon monoxide. Embryos which were exposed to CP (25 mg/kg) in vivo on Day 10 were indistinguishable from embryos treated in vitro. All developed characteristic defects and had significant decreases in growth parameters when compared to control litters receiving only vehicle. No histological differences were seen between embryos treated in vivo or in vitro. These data provide further evidence that the teratogenicity of CP is dependent upon one or more maternal P450 monooxygenase systems.
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107
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Juchau MR, Namkung J, Chao ST. Mono-oxygenase induction in the human placenta. Interrelationships among position-specific hydroxylations of 17 beta-estradiol and benzo[a]pyrene. Drug Metab Dispos 1982; 10:220-4. [PMID: 6125353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
An investigation of the specific hydroxylations of aromatic ring carbon atoms 2 and 4 of 17 beta-estradiol (E2) in microsomal fractions of human placental tissues revealed that rates of 4-hydroxylation were elevated 3- to 5-fold in placentas of cigarette smokers. Minor increases in hydroxylation at carbon atom 2 were statistically insignificant. Correlation analyses and studies with inhibitors and activators also strongly indicated that 2-hydroxylase and 4-hydroxylase activities were under separate regulatory control. Attempts to determine possible correlations between placental E2 4-hydroxylase and aryl hydrocarbon (benzo[a]pyrene, BaP) hydroxylase (AHH) activities revealed an unusual threshold-type relationship. With AHH activities of 0-40 pmol/mg/15 min, no-statistically significant correlation existed. With AHH activities above 50 pmol/mg/15 min, E2 4-hydroxylase activities were markedly elevated but, in the range of 50- 180 pmol/mg/15 min, statistically significant correlations again were not observed. Analysis also were performed on the relationships of E2 2- and 4-hydroxylations to BaP metabolism as assessed with high-pressure liquid chromatography (HPLC). Strong positive correlations were observed between quantities of nearly all measured BaP metabolites and 4-hydroxy- but not 2-hydroxy-E2. The threshold effect again was evident. E2 exhibited only weak activity as an inhibitor of placental BaP hydroxylation as measured fluorimetrically or with HPLC. BaP effectively inhibited E2 4-hydroxylase activities at comparatively low inhibitor concentrations but inhibited E2 2-hydroxylase activities only weakly. Analyses of the effects of a series of modifiers on the three measured mono-oxygenase activities also suggested that each activity was under separate regulatory control.
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108
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Juchau MR, Chao ST, Namkung MJ. Metabolism of polycyclic aromatic hydrocarbons in placenta. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1982; 136 Pt A:555-67. [PMID: 7344479 DOI: 10.1007/978-1-4757-0674-1_41] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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109
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Omiecinski CJ, Namkung MJ, Juchau MR. Substrate and position specificity of hematin-activated monooxygenation reactions. Biochem Pharmacol 1981; 30:2837-45. [PMID: 7317078 DOI: 10.1016/0006-2952(81)90423-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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110
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Fantel AG, Greenaway JC, Shepard TH, Juchau MR, Selleck SB. The teratogenicity of cytochalasin D and its inhibition by drug metabolism. TERATOLOGY 1981; 23:223-31. [PMID: 7268639 DOI: 10.1002/tera.1420230207] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Pregnant rats received intraperitoneal injections of cytochalasin D (CD) on gestational days 7-11. Doses of 400 micrograms/kg were only minimally and nonsignificantly teratogenic, leading to 2 exencephalic fetuses among the 111 fetuses delivered. By contrast, embryos exposed to CD in vitro on day 10 showed significant frequencies of neural tube abnormalities when exposed to CD concentrations at or above 3.1 ng/ml. These embryos also exhibited significantly decreased protein, somite counts, and crown-rump lengths. In order to understand this apparent discrepancy between the teratogenicity of CD in vivo and in vitro we performed experiments to determine whether drug metabolism could inhibit the teratogenicity in vitro. Male rats were pretreated with a mixture of polychlorinated biphenyls as cytochrome P-450 inducers, and their livers were used to prepare a microsome-rich fraction (S-9). This S-9 fraction, plus a source of reducing equivalents (NADPH), significantly inhibited the teratogenicity of CD. The teratogenicity was restored by the omission of NADPH, and was partially restored with the addition of carbon monoxide. These results led us to conclude that the teratogenic effect of CD can be inhibited by drug metabolism in vitro; additionally, it is likely that some or all of this drug metabolism may depend on cytochrome P-450. We further speculate that CD may be inactivated in vivo by these same systems, explaining the discrepancy between the teratogenicity of CD in vivo and in vitro.
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111
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Bond JA, Gown AM, Yang HL, Benditt EP, Juchau MR. Further investigations of the capacity of polynuclear aromatic hydrocarbons to elicit atherosclerotic lesions. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH 1981; 7:327-35. [PMID: 6262518 DOI: 10.1080/15287398109529983] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Treatment of chickens for up to 20 wk with varying doses (0.1-10 mg/kg) of benzo[a]pyrene (BaP) or 7,12-dimethylbenz[a]anthracene (DMBA) resulted in significant increases in incidence and size of atherosclerotic lesions at the two higher doses utilized (1 and 10 mg/kg). Maximal lesion formation for birds treated chronically with BaP occurred at 1 mg/kg, while development of lesions in birds treated with DMBA was roughly linear over the dose range tested. The largest doses of BaP or DMBA (10 mg/kg for 20 wk) produced the highest percentage of chickens with detectable lesions (75 and 89%, respectively). Lower doses of BaP or DMBA resulted in a smaller percentage of birds (per group) with lesions, and the lowest dose (0.1 mg/kg) produced no statistical increase in lesion incidence. At approximately equimolar doses, DMBA appeared to be more potent than BaP in enhancing the development of lesions in the chickens. Administration of a single dose of BaP or DMBA followed by weekly doses of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) for 20 wk did not result in enhancement of lesion formation over the respective controls. Blood cholesterol was not significantly altered after treatment of chickens with DMBA, BaP, or TPA.
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112
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Namkung MJ, Juchau MR. On the capacity of human placental enzymes to catalyze the formation of diols from benzo[a]pyrene. Toxicol Appl Pharmacol 1980; 55:253-9. [PMID: 7423515 DOI: 10.1016/0041-008x(80)90087-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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113
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Abstract
A review of the literature that pertains to drug biotransformation in human fetal tissues reveals that, in spite of several publications in this comparatively new area of research, only very limited definitive information is currently available. The large majority of the studies performed have dealt with the cytochrome P-450-dependent microsomal mono-oxygenase systems and for several of the common drug metabolising reactions, very little or no data are available at this time. Some of the more important data that have emerged include observations that important bioactivation reactions can be demonstrated in human fetal tissues obtained during the period of late embryogenesis (high susceptibility to chemical dysmorphogenesis) and that the human fetal adrenal gland possesses considerable capacity to catalyse several important oxidation-reduction reactions. From the data available to date, it would appear that, in most instances, the biotransformation of drugs in the human embryo and fetus would not affect maternal plasma concentrations significantly. From the viewpoint of parameters of the pharmacokinetics of parent drug (or other xenobiotic) substrates under steady-state conditions, human fetal drug metabolism probably is of little consequence in most cases, although exceptions may exist. Pharmacokinetic parameters observed after isolated exposure, however, are very likely to be affected, perhaps markedly, in some instances. The demonstrated capacity of human prenatal tissues and cells to generate reactive intermediary metabolites, including those that produce mutations, has attracted the greatest attention recently. This capacity may be associated with extremely important adverse reactions to drugs and other environmental chemicals. Such adverse responses include transplacental mutagenesis, carcinogenesis, dysmorphogenesis, and perhaps several other undesirable effects. Although far from conclusive, the data tend to suggest that humans and subhuman primates may be more vulnerable than the smaller common experimental animals to the toxic effects of foreign organic chemicals during prenatal life. These factors should be weighed whenever exposure of pregnant women to such agents (e.g. via drug administration) is contemplated.
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114
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Omiecinski CJ, Namkung MJ, Juchau MR. Mechanistic aspects of the hematin-mediated increases in brain monooxygenase activities. Mol Pharmacol 1980; 17:255-32. [PMID: 7393206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
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115
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Chao ST, Juchau MR. Interactions of endogenous and exogenous estrogenic compounds with human placental microsomal cytochrome P-450 (P-450hpm). JOURNAL OF STEROID BIOCHEMISTRY 1980; 13:127-33. [PMID: 7382489 DOI: 10.1016/0022-4731(80)90183-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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116
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Bond JA, Yang HY, Majesky MW, Benditt EP, Juchau MR. Metabolism of benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene in chicken aortas: monooxygenation, bioactivation to mutagens, and covalent binding to DNA in vitro. Toxicol Appl Pharmacol 1980; 52:323-35. [PMID: 6244684 DOI: 10.1016/0041-008x(80)90119-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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117
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Chao ST, Juchau MR. Cytochrome P-450 mixed function oxygenases in placental tissue: metabolism of endogenous and exogenous compounds. PROCEEDINGS OF THE WESTERN PHARMACOLOGY SOCIETY 1980; 23:3-7. [PMID: 6773060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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118
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119
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DiGiovanni J, Juchau MR. Biotransformation and bioactivation of 7, 12-dimethylbenz[a]anthracene (7, 12-DMBA). Drug Metab Rev 1980; 11:61-101. [PMID: 6775921 DOI: 10.3109/03602538008994022] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
As the result of rapidly developing technological advances, our understanding of the biotransformation and bioactivation of 7, 12-DMBA has increased markedly in recent years. In terms of the metabolic conversion of this polynuclear aromatic hydrocarbon to reactive mutagen/carcinogens, the "bay region" generalization appears to apply, although the candidacy of a number of other intermediary metabolites as ultimate biologically-active forms still remains viable. Large gaps remain in knowledge concerning the nonoxidative metabolic transformations of 7, 12-DMBA, and these require closing in order to further our understanding of the regulation of mechanics controlling steady-state levels of reactive intermediates. Studies on the photooxidation of the hydrocarbon have allowed a stronger appreciation of its chemical reactivity and instability and promise to help resolve many of the apparently conflicting observations of the past. 7, 12-DMBA remains a highly interesting and valuable tool in investigations of bioactivation processes as they relate to the etiology of several important pathologic conditions, including chemically induced tissue necrosis, mutagenesis, carcinogenesis, teratogenesis, atherogenesis, and, possibly, other pathogenic phenomena as well. It is hoped that this review will serve to benefit research in these areas and hasten the reduction of such pathologic phenomena in our society.
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120
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DiGiovanni J, Berry DL, Slaga TJ, Jones AH, Juchau MR. Effects of pretreatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin on the capacity of hepatic and extrahepatic mouse tissues to convert procarcinogens to mutagens for Salmonella typhimurium auxotrophs. Toxicol Appl Pharmacol 1979; 50:229-39. [PMID: 388724 DOI: 10.1016/0041-008x(79)90148-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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121
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Bond JA, Kocan RM, Benditt EP, Juchau MR. Metabolism of benzo[a]pyrene and 7,12-dimethylbenz[a]anthracene in cultured human fetal aortic smooth muscle cells. Life Sci 1979; 25:425-30. [PMID: 113639 DOI: 10.1016/0024-3205(79)90574-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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122
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Fantel AG, Greenaway JC, Juchau MR, Shepard TH. Teratogenic bioactivation of cyclophosphamide in vitro. Life Sci 1979; 25:67-72. [PMID: 481123 DOI: 10.1016/0024-3205(79)90491-0] [Citation(s) in RCA: 167] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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123
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Juchau MR, DiGiovanni J, Namkung MJ, Jones AH. A comparison of the capacity of fetal and adult liver, lung, and brain to convert polycyclic aromatic hydrocarbons to mutagenic and cytotoxic metabolites in mice and rats. Toxicol Appl Pharmacol 1979; 49:171-8. [PMID: 382440 DOI: 10.1016/0041-008x(79)90288-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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124
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DiGiovanni J, Romson JR, Linville D, Juchau MR, Slaga TJ. Covalent binding of polycyclic aromatic hydrocarbons to adenine correlates with tumorigenesis in mouse skin. Cancer Lett 1979; 7:39-43. [PMID: 110439 DOI: 10.1016/s0304-3835(79)80074-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mouse epidermal homogenates were utilized to convert various polycyclic aromatic hydrocarbons to metabolites capable of binding covalently with nucleic acids. Poly(G) showed the highest capacity to bind covalently with the hydrocarbons; however, there was no correlation between binding to poly(G) and mouse skin tumorigenicity. On the other hand, covalent binding to poly(A) correlated well with values obtained for binding to DNA and mouse skin tumorigenicity. The order of binding to poly(A) was; 7,12-dimethylbenza[a]anthracene greater than benzo[a]pyrene greater than dibenz[a,h]anthracene greater than dibenz[a,c]anthracene.
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125
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Berry DL, Slaga TJ, DiGiovanni J, Juchau MR. Studies with chlorinated dibenzo-p-dioxins, polybrominated biphenyls, and polychlorinated biphenyls in a two-stage system of mouse skin tumorigenesis: potent anticarcinogenic effects. Ann N Y Acad Sci 1979; 320:405-14. [PMID: 222192 DOI: 10.1111/j.1749-6632.1979.tb56621.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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126
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Gilbert RD, Cummings LA, Juchau MR, Longo LD. Placental diffusing capacity and fetal development in exercising or hypoxic guinea pigs. JOURNAL OF APPLIED PHYSIOLOGY: RESPIRATORY, ENVIRONMENTAL AND EXERCISE PHYSIOLOGY 1979; 46:828-34. [PMID: 457563 DOI: 10.1152/jappl.1979.46.4.828] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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127
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DiGiovanni J, Berry DL, Juchau MR, Slaga TJ. 2,3,7,8-Tetrachlorodibenzo-P-dioxin: potent anticarcinogenic activity in CD-1 mice. Biochem Biophys Res Commun 1979; 86:577-84. [PMID: 106852 DOI: 10.1016/0006-291x(79)91752-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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128
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Bond JA, Omiecinski CJ, Juchau MR. Kinetics, activation, and induction of aortic mono-oxygenases--biotransformation of benzo[a]pyrene. Biochem Pharmacol 1979; 28:305-11. [PMID: 34402 DOI: 10.1016/0006-2952(79)90520-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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129
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Omiecinski CJ, Bond JA, Juchau MR. Stimulation by hematin of monooxygenase activity in extra-hepatic tissues from rats, rabbits and chickens. Biochem Biophys Res Commun 1978; 83:1004-11. [PMID: 708418 DOI: 10.1016/0006-291x(78)91495-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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130
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DiGiovanni J, Slaga TJ, Viaje A, Berry DL, Harvey RG, Juchau MR. Effects of 7, 8-benzoflavone on skin tumor-initiating activities of various 7- and 12-substituted derivatives of 7, 12-dimethylbenz[a]anthracene in mice. J Natl Cancer Inst 1978; 61:135-40. [PMID: 97391 DOI: 10.1093/jnci/61.1.135] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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131
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Juchau MR, Namkung MJ, Jones AH, DiGiovanni J. Biotransformation and bioactivation of 7,12-dimethylbenz[a]anthracene in human fetal and placental tissues. Analyses of HPLC profiles and studies with Salmonella typhimurium. DRUG METABOLISM AND DISPOSITION: THE BIOLOGICAL FATE OF CHEMICALS 1978; 6:273-81. [PMID: 26548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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132
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Berry DL, DiGiovanni J, Juchau MR, Bracken WM, Gleason GL, Slaga TJ. Lack of tumor-promoting ability of certain environmental chemicals in a two-stage mouse skin tumorigenesis assay. RESEARCH COMMUNICATIONS IN CHEMICAL PATHOLOGY AND PHARMACOLOGY 1978; 20:101-8. [PMID: 208126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The food antioxidants butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) were tested as tumor promoters on CD1 female mice initiated with 7, 12-dimethylbenz(a)anthracene (DMBA). At a dose of 1 mg twice weekly they did not promote skin tumors. Nor did they produce tumors when tested as a complete carcinogen without DMBA initiation. The polychlorinated biphenyl Aroclor 1254 (PCB) and the polybrominated biphenyl Firemaster-6 (PBB) were also tested for their ability to promote skin tumors; at a 100 microgram dose twice weekly they were inactive. The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at a dose of 0.1 microgram twice weekly did not promote skin tumors in DMBA-initiated mice. TCDD, PCB, and PBB did not promote spontaneous tumors. None of the compounds at the dosages tested significantly increased the intrafollicular epidermis, nor did they appear to be chronically toxic to the test animals. These results indicate that dosage may be an important factor in promotion, since several of the tested compounds are known to be promoters in pulmonary and hepatic systems.
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133
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Jones AH, Fantel AG, Kocan RA, Juchau MR. Bioactivation of procarcinogens to mutagens in human fetal and placental tissues. Life Sci 1977; 21:1831-5. [PMID: 342853 DOI: 10.1016/0024-3205(77)90165-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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134
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Berry DL, Bracken WR, Slaga TJ, Wilson NM, Butty SG, Juchau MR. Benzo(a)pyrene metabolism in mouse epidermis. Analysis by high pressure liquid chromatography and DNA binding. Chem Biol Interact 1977; 18:129-42. [PMID: 890843 DOI: 10.1016/0009-2797(77)90001-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Mouse epidermal homogenates contain an inducible aryl hydrocarbon hydroxylase (AHH) complex that catalyzes the formation of benzo(a)pyrene-7,8-dihydrodiol from benzo(a)pyrene (BP) as assessed by high pressure liquid chromatography (HPLC). 5,6-Benzoflavone (5,6-BF), 7,8-benzoflavone (7,8-BF) and 17-beta-estradiol decreased and butylated hydroxytoluene (BHT) enhanced oxidative metabolism of BP when added in vitro. Epoxide hydrase activity (hydration of benzo(a)pyrene-4,5-epoxide) (BP-4,5-epoxide) was enhanced by 17-beta-estradiol, 5,6-BF, and 7,8-BF. BHT exhibited no significant effect and 1,2-epoxy-3,3,3-trichloropropane (TCPO) inhibited hydrase activity. The capacity of epidermal homogenates to catalyze the covalent binding of BP to DNA indicated that addition of both 5,6-BF and 7,8-BF decreased binding. BHT and TCPO did not significantly affect DNA-binding.
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Berry DL, Slaga TJ, Wilson NM, Zachariah PK, Namkung MJ, Bracken WM, Juchau MR. Transplacental induction of mixed-function oxygenases in extra-hepatic tissues by 2,3,7,8-tetrachlorodibenzo-p-dioxin. Biochem Pharmacol 1977; 26:1383-8. [PMID: 901552 DOI: 10.1016/0006-2952(77)90361-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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136
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Zachariah PK, Slaga TJ, Berry DL, Bracken WM, Buty SG, Martinsen CM, Juchau MR. The ability of enteric bacteria to catalyze the covalent binding of bile acids and cholesterol to DNA and their in ability to metabolize benzo(a)pyrene to a binding product and to known metabolites. Cancer Lett 1977; 3:99-105. [PMID: 19150 DOI: 10.1016/s0304-3835(77)94577-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The capacity of enteric bacteria (E. coli, Salmonella, Pseudomonas, Shigella and Klebsiella) to catalyze the covalent binding of benzo(a)pyrene (BP), cholic acid, deoxycholic acid and cholesterol was investigated. In general, these bacteria were incapable of activating BP to a covalently bound product with calf thymus DNA. Metabolism studies of BP by fluorometric assay failed to indicate any accumulation of BP-3-hydroxy in the incubation medium. Detailed metabolic investigation with high-pressure liquid chromatography indicated that these bacteria did not produce any known metabolites which are formed by mammalian systems. However, radioactivity was detected in all fractions, suggesting that the bacteria were readily metabolizing BP into smaller molecules for energy and carbon sources. Although the enteric bacteria did not metabolize BP into known metabolites, some were capable of activating cholesterol, cholic acid and deoxycholic acid to covalently bound products with DNA. The binding data with cholesterol and bile acids also suggested that the binding process required NADPH as a cofactor because binding level was rather low without NADPH.
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Berry DL, Zachariah PK, Slaga TJ, Juchau MR. Analysis of the biotransformation of benzo [a] pyrene in human fetal and placental tissues with high-pressure liquid chromatography. Eur J Cancer 1977; 13:667-75. [PMID: 413719 DOI: 10.1016/0014-2964(77)90052-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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138
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Hodgson E, Juchau MR. Ligand binding to human placental cytochrome P-450: interaction of steroids and heme-binding ligands. JOURNAL OF STEROID BIOCHEMISTRY 1977; 8:669-75. [PMID: 592792 DOI: 10.1016/0022-4731(77)90295-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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139
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Slaga TJ, Thompson S, Berry DL, Digiovanni J, Juchau MR, Viaje A. The effects of benzoflavones on polycyclic hydrocarbon metabolism and skin tumor initiation. Chem Biol Interact 1977; 17:297-312. [PMID: 407010 DOI: 10.1016/0009-2797(77)90093-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The effects of benzoflavones on skin tumor initiation by polycyclic hydrocarbons and epidermal aryl hydrocarbon hydroxylase were investigated. 7,8-Benzoflavone (7,8-BF) was found to be a potent inhibitor of the inhibition of skin tumors by 3-methylcholanthrene (MC) as well as 7,12-dimethylbenz(a)anthracene (DMBA). 5,6-Benzoflavone(5,6-BF) inhibited tumor initiation by MC and DMBA, but to a lesser degree than 7,8-BF. Dose-response studies of the capacity of 7,8-BF to inhibit DMBA tumor initiation revealed that 7,8-BF was an effective inhibitor at 2.5 microgram and a maximum inhibition of 90% occurred at 100 microgram of 7,8-FB. The tumor initiating ability of 7-hydroxymethyl-12-methylbenz(a)anthracene (7-OHMe-12MeBA) was not inhibited by 7,8-BF. Epidermal aryl hydrocarbon(benzo(a)pyrene hydroxylase(AHH) was increased by 5,6-BF and either had no effect or was slightly inhibited by 7,8-BF when given either topically or i.p. Both flavones when added directly to the assay tubes inhibited the in vitro epidermal AHH activity from control and MC pretreated mice by greater than 75%. When added in vitro, 7,8-BF and 5,6-BF inhibited epidermally mediated covalent binding of radioactive DMBA and dibenz(a,h)anthracene to DNA by 50% or more. The inhibition of skin tumor initiation by 7,8-BF and 5,6-BF appears to be partially related to its ability to inhibit the formation of electrophilic intermediates.
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140
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DiGiovanni J, Slaga TJ, Berry DL, Juchau MR. Metabolism of 7,12-dimethylbenz[a]anthracene in mouse skin homogenates analyzed with high-pressure liquid chromatography. DRUG METABOLISM AND DISPOSITION: THE BIOLOGICAL FATE OF CHEMICALS 1977; 5:295-301. [PMID: 17529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The metabolism of 7,12-dimethylbenz[a]anthracene (DMBA) in epidermal homogenates from 3-methylcholanthrene-pretreated mice was analyzed with high-pressure liquid chromatography. Metabolism was undetectable in the absence of pretreatment. Specific activities in epidermal homogenates from pretreated mice were found to be approximately 100 to 1000 times lower than those observed in comparable incubations containing hepatic microsomes from MC-pretreated rats. The major metabolite formed was identified as 7-hydroxymethyl-12-methylbenz[a]anthracene. Each of the known hydroxymethyl metabolites also was present in detectable quantities. The K-region diol was not measurably present in incubations with mouse skin homogenates or rat liver microsomes from MC-pretreated animals. 7,8-Benzoflavone, 5,6-benzoflavone, and 17-beta-estradiol were found to be potent inhibitors of the metabolic transformation of DMBA by epidermal homogenates in vitro, whereas butylated hydroxytoluene and 1,1,1-trichloro-2,3-propene oxide had little effect on or enhanced metabolite formation from DMBA in vitro.
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141
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Namkung MJ, Zachariah PK, Juchau MR. O-sulfonation of N-hydroxy-2-fluorenylacetamide and 7-hydroxy-N-2-fluorenylacetamide in fetal and placental tissues of humans and guinea pigs. DRUG METABOLISM AND DISPOSITION: THE BIOLOGICAL FATE OF CHEMICALS 1977; 5:288-94. [PMID: 17528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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142
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Berry DL, Slaga TJ, Viaje A, Wilson NM, DiGiovanni J, Juchau MR, Selkirk JK. Effect of trichloropropene oxide on the ability of polyaromatic hydrocarbons and their "K-region" oxides to initiate skin tumors in mice and to bind to DNA in vitro. J Natl Cancer Inst 1977; 58:1051-5. [PMID: 403293 DOI: 10.1093/jnci/58.4.1051] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The potent epoxide hydrase inhibitor, 1,1,1-trichloro-2,3-propene oxide (TCPO), enhanced the tumor-initiating ability of benzo[alpha]pyrene (BP) and 3-methylcholanthrene (MCA) but had no effect on 9,10-dimethyl-1,2-anthracene (DMBA) initiation in a two-stage system of tumorigenesis in female Charles River CD-1 mice. The tumor-initiating ability of dibenz[alpha,h]-anthracene (DBA) was decreased by prior topical treatment with 10 mumoles of TCPO. The tumor latency period of BP and MCA was decreased by TCPO but had no effect on DMBA or DBA. Topical treatment with 10 mumoles of TCPO did not initiate tumors in a two-stage system in mouse skin nor did it cause any histopathologic changes in the skin. The "K-region" epoxides of BP, DMBA, and MCA were weak tumor initiators when compared to the parent compounds. TCPO only slightly increased or had no effect on the tumor-initiating activity of the above epoxides. Pretreatment with Croton oil 18 hours prior to initiation with BP-4,5-epoxide also slightly enhanced the tumorigenic response in mouse skin. DBA-5,6-epoxide, when tested as a complete carcinogen at high doses (1 mg daily/10 days), was found to be a weak carcinogen but with activity comparable to that of DBA. TCPO only slightly increased the in vitro epidermally mediated covalent binding of the above parent polycyclic hydrocarbons to DNA.
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Zachariah PK, Juchau MR. Inhibition of human placental mixed-function oxidations with carbon monoxide: reversal with monochromatic light. JOURNAL OF STEROID BIOCHEMISTRY 1977; 8:221-8. [PMID: 859324 DOI: 10.1016/0022-4731(77)90055-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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144
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Juchau MR, Mirkin DL, Zachariah PK. Interactions of various 19-nor steroids with human placental microsomal cytochrome P-450 (P-450hpm). Chem Biol Interact 1976; 15:337-47. [PMID: 12875 DOI: 10.1016/0009-2797(76)90139-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Each of seven 19-nor steroids exhibited the capacity to facilitate the binding of carbon monoxide (CO) to human placental microsomal cytochrome P-450 although quantitative differences were shown to exist. In every case the facilitation was antagonized by androstenedione. 19-Norandrostenedione produced the most pronounced effect followed by 19-nortestosterone, nandrolone decanoate, norethandrolone, norgestrel, norethynodrel and norethindrone in that order. All steroids investigated produced typical type I binding spectra when added to placental microsomes. Scatched plots also indicated binding of each steroid to two sites--a high-affinity, low-capacity binding site and a low-affinity, high-capacity binding site. Correlations between affinity for either site and capacity to facilitate binding of CO to the cytochrome were not observed nor were there good correlations between maximal absorbance differences (approximately390-420 nm) producible and facilitation capacity. It was therefore concluded that no definitive relationships existed between facilitation capacity and qualitative or quantitative aspects of the steroid-binding spectra. The capacity to facilitate CO binding appeared to reside in the absence of a chemical group substituted at the 10 position on molecules of androgenic steroids since all investigated steroids possessing 10-methyl or other 10-substituted groups either had no effect on the CO-binding spectrum or caused a displacement of CO from ferrous heme. In contrast, all steroids studied that lacked a substitution at C-10 (19-nor steroids) produced a facilitating effect on heme-ligand binding.
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Juchau MR, Bond JA, Benditt EP. Aryl 4-monooxygenase and cytochrome P-450 in the aorta: possible role in atherosclerosis. Proc Natl Acad Sci U S A 1976; 73:3723-5. [PMID: 824648 PMCID: PMC431191 DOI: 10.1073/pnas.73.10.3723] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Aryl 4-monooxygenase [aniline, reduced-flavoprotein:oxygen oxidoreductase (4-hydroxylating); EC 1.14.14.1] activity was searched for and found in homogenates of aorta walls from rabbits, rhesus monkeys, and humans. Specific activities were comparable to activities observed in several other extrahepatic tissues of rabbits and monkeys and in epidermal tissues from mice, but were one to two orders of magnitude lower than those observed in corresponding preparations of hepatic tissues. Cytochrome P-450 also could be detected in low concentrations in microsomal fractions of aortic wall homogenates. The monooxygenase activity found in the aorta could play a significant role in the etiology and pathogenesis of atherosclerosis in humans by catalyzing the conversion of environmental promutagens to mutagenic initiators and/or cytotoxic factors, thus leading to development of benign, smooth muscle tumors of the inner lining of artery walls.
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Berry DL, Zachariah PK, Namkung MJ, Juchau MR. Transplacental induction of carcinogen-hydroxylating systems with 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol Appl Pharmacol 1976; 36:569-84. [PMID: 941154 DOI: 10.1016/0041-008x(76)90236-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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147
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Zachariah PK, Lee QP, Symms KG, Juchau MR. Further studies on the properties of human placental microsomal cytochrome P-450. Biochem Pharmacol 1976; 25:793-800. [PMID: 7272 DOI: 10.1016/0006-2952(76)90149-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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148
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Lee QP, Zachariah PK, Juchau MR. Differential inhibition of androst-4-en-3,17-dione aromatization by carbon monoxide in the presence of estr-4-en-3,17-dione. Steroids 1975; 26:571-8. [PMID: 1209686 DOI: 10.1016/0039-128x(75)90051-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The aromatization of androst-4-en-3,17-dione or 17beta hydroxyandrost-4-en-3-one (testosterone) is not inhibited by carbon monoxide under normal incubation conditions, whereas the aromatization of corresponding 19-nor steroids (estr-4-en-3,17-dione and 17beta-hydroxyestr-4-en-3-one) is readily inhibited under the same conditions. A possible explanation was found when it was shown that androst-4-en-3,17-dione and testosterone could displace bound carbon monoxide from human placental microsomal cytochrome P-450. The 19-nor steroids did not displace carbon monoxide, even at very high concentrations. These C-18 compounds appeared to facilitate complex formation and reversed the effects of the C-19 steroids. A mutual antagonism was observed with regard to effects on the formation of the ce titrated. These observations suggested that the aromatization of androst-4-en-3,17-dione should be inhibited by carbon monoxide if sufficient concentrations of the 19-nor steroids were present in reaction flasks. This hypotheses was tested and positive results were obtained, providing strong evidence for the involvement of cytochrome P-450 in normal estrogen biosynthesis.
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Juchau MR, Namkung MJ, Berry DL, Zachariah PK. Oxidative biotransformation of 2-acetylaminofluorene in fetal and placental tissues of humans and monkeys. Correlations with aryl hydrocarbon hydroxylase activities. DRUG METABOLISM AND DISPOSITION: THE BIOLOGICAL FATE OF CHEMICALS 1975; 3:493-501. [PMID: 1224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mixed-function oxidation of 14C-labled 2-acetylaminofluorene (AAF) was investigated in placental and fetal tissues of humans and monkeys (Macaca nemestrina) in vitro. The major metabolite formed in most tissues was 7-hydroxy-AAF. Rates of the hydroxylation reactions varied widely among the tissues investigated and were generally one to two orders of magnitude lower than those measured in rat hepatic tissues. High correlations among rates of 7-,5-, and 3- and between 1- and N-hydroxylations of AAF were observed. The latter two reactions were less responsive to inhibition by carbon monoxide. Rates of 3-hydroxylations of benzo[a]pyrene (BP) also were highly correlated with rates of 7-, 5-, and 3-hydroxylations of AAF but were not correlated with rates of 1- and N-hydroxylations in human placental microsomes. A lack of statistically significant correlations was observed among rates of many of these hydroxylation reactions studied in primate fetal tissues. Rates of 7-, 5-, and 3-hydroxylations of AAF were not statistically correlated with rates of 3-hydroxylation of BP in homogenates of primate fetal tissues in most instances, but statistically significant correlations among rates of 3-hydroxylation of BP and 1- and N-hydroxylations of AAF were observed in those preparations. The results suggested two separate mechanisms for the genetic control of rates of placental aromatic ring- and N-hydroxylation reactions as opposed to apparent multiple genetic controls for rates of these hydroxylation reactions in primate fetal tissues.
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Juchau MR, Zachariah PK. Displacement of carbon monoxide from placental cytochrome P-450 by steroids: antagonistic effects of androstenedione and 19-norandrostenedione. Biochem Biophys Res Commun 1975; 65:1026-32. [PMID: 239710 DOI: 10.1016/s0006-291x(75)80488-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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