Markku Pasanen - Academia.edu (original) (raw)
Papers by Markku Pasanen
Biochemical Pharmacology, Feb 1, 1996
The expression of individual xenobiotic-metabolizing cytochrome P450 (CYP) genes in human placent... more The expression of individual xenobiotic-metabolizing cytochrome P450 (CYP) genes in human placenta was studied at the mRNA level by reverse transcriptase-polymerase chain reaction (RT-PCR). mRNAs of CYP1A1, CYP2E1, CYP2F1, CYP3A3/4, CYP3A5, and CYP4B1 were detected by RT-PCR, and CYP1A2, CYP2A6/7, CYP2B6/7, CYp2C8-19, CYP2D6, and CYp3A7 were not detected. Several enzyme activity assays and immunoblasts were used to further characterize expression of forms producing detectable mRNA transcripts. The catalytic activities of 7-ethoxycoumarin O-deethylase (ECOD), 7-ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxylase (AHH) were substantially increased in response to maternal cigarette smoking, and paralleled the amount of CYP1A1 mRNA and protein. Aromatase activities were slightly lower in placentas exposed to cigarette smoke compared with nonexposed placentas. These data show that several xenobiotic-metabolizing CYP genes are expressed in human placenta at a low level. The significant of such low-level expression is unknown, but it may have local physiological or toxic consequences.
South African Journal of Botany, Mar 1, 2018
the extraction techniques of the white flowering Nerium oleander L. (Apocynaceae) and commercial ... more the extraction techniques of the white flowering Nerium oleander L. (Apocynaceae) and commercial feeds. Organic (hexane, acetone and methanol) sequential and aqueous (infusion and decoction) extractions were explored. Subsequently, a qualitative and HPLC quantitative analysis was carried out to compare contents of ANFs where the Mann Whitney U statistical tool was used at a threshold level of 0.05. The results showed higher extraction yields in all aqueous extractions. Therefore, an infusion may be considered as the best approach to mitigate plant poisoning due by ANFs in plants since it proved to be an efficient, safe and reliable method. Furthermore, although the results were not so significant (p b 0.05), a high saponin content of 0.113 ± 0.104 mg/g in diosgenin equivalent was obtained in commercial feeds. In addition, LC-MS will be conducted to characterise the quantified ANFs from the sample.
Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
A comprehensive set of 3-phenylcoumarin analogues with polar substituents was synthesised for blo... more A comprehensive set of 3-phenylcoumarin analogues with polar substituents was synthesised for blocking oestradiol synthesis by 17-b-hydroxysteroid dehydrogenase 1 (HSD1) in the latter part of the sulphatase pathway. Five analogues produced !62% HSD1 inhibition at 5 mM and, furthermore, three of them produced !68% inhibition at 1 mM. A docking-based structure-activity relationship analysis was done to determine the molecular basis of the inhibition and the cross-reactivity of the analogues was tested against oestrogen receptor, aromatase, cytochrome P450 1A2, and monoamine oxidases. Most of the analogues are only modestly active with 17-b-hydroxysteroid dehydrogenase 2a requirement for lowering effective oestradiol levels in vivo. Moreover, the analysis led to the synthesis and discovery of 3-imidazolecoumarin as a potent aromatase inhibitor. In short, coumarin core can be tailored with specific ring and polar moiety substitutions to block either the sulphatase pathway or the aromatase pathway for treating breast cancer and endometriosis.
Reproductive Toxicology, 2021
Journal of Psychiatric Research, 2021
Alternatives to Laboratory Animals, 2005
European Journal of Cancer and Clinical Oncology, 1987
Biochemical Journal, 2016
Polyamine metabolism is an attractive anticancer drug target, since polyamines are absolutely req... more Polyamine metabolism is an attractive anticancer drug target, since polyamines are absolutely required for cellular proliferation, and increased levels of polyamines and their biosynthetic enzyme ornithine decarboxylase (ODC) are associated with cancer. Triethylenetetramine (TETA) is a charge-deficient isosteric analogue of the polyamine spermidine (Spd) and a Cu(II)-chelating compound used for the treatment of Wilson's disease, and it has been implicated as a potential anticancer therapeutic drug. In the present study, we studied the effects of TETA in comparison with two other Cu(II)-chelators, D-penicillamine (PA) and tetrathiomolybdate (TTM), on polyamine metabolism in DU145 prostate carcinoma, MCF-7 breast carcinoma and JEG-3 choriocarcinoma cells. TETA induced antizyme, down-regulated ODC and inhibited [14C] Spd uptake. Moreover, it completely prevented α-difluoromethylornithine (DFMO)-induced increase in [14C] Spd uptake, and inhibited [14C] putrescine (Put) uptake and OD...
Monografias De La Real Academia Nacional De Farmacia, 2004
La seleccion de especies animales optimas que puedan servir para estudiar el metabolismo de farma... more La seleccion de especies animales optimas que puedan servir para estudiar el metabolismo de farmacos en humanos es todavia un gran reto en el programa de desarrollo de farmacos. Las especies utilizadas en estudios de metabolismo deberian tambien incluir parametros de toxicidad relacionados con el metabolismo. El uso de proteinas CYP recombinantes humanas y de sistemas de expresion no puede resolver este problema. Las especies mas usadas en estudios metabolicos son: raton, rata, conejo, perro y mono, y en menor grado cobayas y hamsters. Todos ellos son de alguna manera defectivos en su perfil de CYP cuando se comparan al humano. Por ejemplo, la presencia del enzima CYP1A2 en mono es controvertida; las actividades marcadoras clasicas de los CYP2C y CYP2E en perro estan cuestionadas; el CYP2A de higado de rata no cataliza la reaccion de la 7-hidroxilacion de la cumarina; la CYP2D de cerdo no cataliza la reaccion de la hidroxilacion de la debrisoquina y diversas otras formas CYP tienen pesos moleculares diferentes a los CYP humanos o de rata. Excepto en el hombre y la rata, las proporciones relativas de diversas formas CYP a nivel basal no han sido investigadas y cuantificadas en otras especies. Aunque los primates no humanos se han considerado el mejor modelo para estudiar el metabolismo de farmacos en humanos, debido a rezones eticas el uso de monos puede no ser la primera opcion para el estudio in vivo de las caracteristicas metabolicas de una nueva entidad quimica. Debido a las diferencias dependientes de las especies en la estructura primaria de las distintas formas CYP y en la expresion genica que conduce las cascadas reguladoras, pueden encontrarse notables diferencias en el nivel basal de la expresion de CYP en su inducibilidad y en las propiedades de union a sustratos, inhibidores y anticuerpos. Por tanto, el principal obstaculo en la interpretacion de los resultados asociados a CYP de una especie a otra es la carencia de conocimientos basicos necesarios para hacer el diagnostico en otras especies.
Translationaalinen lääketutkimus ja -kehitys
Placenta, 2000
We investigated the effects of maternal gestational corticosteroid therapy on placental xenobioti... more We investigated the effects of maternal gestational corticosteroid therapy on placental xenobiotic and steroid metabolizing enzymes at term in 20 glucocorticoid/betamethasone treated (with various doses) and control (n=10) women. A single dose of betamethasone (12 mg i.m. twice at a 24-h interval) was given to 15 mothers at risk of preterm delivery to prevent respiratory syndrome in their premature newborns. Five mothers were treated more than once. The gestation time in mothers receiving the glucocorticoid therapy varied from 22-38 gestational weeks. Compared with controls, a significant decrease in placental aromatase activity (53.6+/-18.0 pmol/mg/min versus 119+/-30 pmol/mg/min, P=0.0007) and placental CYP19 mRNA content (by 50 per cent ) was observed in mothers treated with glucocorticoids. Also the formation of androstenedione (13.2+/-8.1 pmol/mg/min, steroids versus 30.03+/-5.2 pmol/mg/min, controls, P< 0.001), using testosterone as the substrate, and 7-ethoxycoumarin O-deethylase (P< 0.05) and 7-ethoxyresorufin O-deethylase (P< 0.09) were slightly decreased in the glucocorticoid treated compared to control patients' values. The changes were not dependent on the number of treatments or the time between treatment and delivery. Our results demonstrate that even a single dose of glucocorticoid given to expectant mothers is associated with diminished placental steroid hormone and xenobiotic metabolizing enzymes at term. Further studies are needed to assess whether these changes affect the well-being of the fetus and its later development.
Journal of Biochemical Toxicology, 1989
The involvement of cytochrome P-450 isozymes in the activation of benzo[a]pyrene (BP) by human pl... more The involvement of cytochrome P-450 isozymes in the activation of benzo[a]pyrene (BP) by human placental and liver microsomes was studied in vitro using monoclonal antibodies (Mab) toward the major 3-methylcholanthrene (MC)-inducible and phenobarbital-inductible rat liver P-450 isozymes (Mab 1-7-1 and Mab 2-66-3, respectively). Microsomes from human placenta and liver and rat liver were incubated with BP and DNA, and BP-diolepoxide-DNA (BPDE-DNA) adducts were measured by synchronous fluorescence spectrophotometry (SFS). The only BP metabolite giving the same fluorescence peak as chemically modified BPDE-DNA was BP-7,8-dihydrodiol. Five (smokers) out of 29 human placentas (smokers and nonsmokers), and five out of nine human livers were able to metabolically activate BP to BPDE-DNA adducts in this system. The Mab 1-7-1 totally inhibited the formation of BPDE-DNA adducts in placental microsomal incubations. Inhibition using rat or human liver microsomes was 50-60% and about 90%, respectively. The Mab 2-66-3 had no effect in any of the microsome types. Adduct formation was inhibited more strongly and at lower concentrations of Mab 1-7-1 compared with the inhibition of AHH activity. This study is a clear indication of the major role of P-450IA1 (P-450c) in human placenta and probably P-450IA2 (P-450d) in human liver in BP activation, while other isozymes also take part in the activation in rat liver. Furthermore, this clearly indicates that AHH activity and BP activation are not necessarily associated.
Biomarkers in Toxicology, 2014
ABSTRACT Nutrient and gas exchange between mother and fetus and production of hormones sustaining... more ABSTRACT Nutrient and gas exchange between mother and fetus and production of hormones sustaining fetal development are important placental functions carried out by a rich selection of transporter proteins and a variety of metabolizing enzymes. The same proteins handle many xenobiotics which in placenta may pass, accumulate, and change placental functions, causing toxicity. Because of structural and functional variation between species, human placental tissue and human trophoblastic cell lines are the most used systems in the search for placental biomarkers of toxicity. They would be helpful in evaluation of drug toxicity in placenta, and in toxicological risk assessment. Only a few exist so far, e.g. changes in CYP19A1/aromatase by hormonally active compounds, metallothioneins in metal exposure, and level of PAH-DNA adducts associated with fetotoxicity. New possibilities are provided, e.g. by the emerging field of placental epigenetics. Use of placenta and placental biomarkers in regulatory toxicology also awaits further data.
Clinical Pharmacology & Therapeutics, 2007
Toxicology Letters, 1994
some cases, not all the responses in single GCTs from the same organ of origin were superimposabl... more some cases, not all the responses in single GCTs from the same organ of origin were superimposable and not all were in accordance with previously published papers.
Steroids, 1984
Cholesterol side-chain cleavage (CSCC) activity towards exogenous cholesterol was quantified by a... more Cholesterol side-chain cleavage (CSCC) activity towards exogenous cholesterol was quantified by an one-step reversed-phase m i n i c o l u m n method for the separation of pregnenolone formed in the reaction. The assay is rapid and reproducible. The method is linear for up to 2 mg of placental m i t o c h o n d r i a l protein and up to I mg of bovine adrenal m i t o c h o n d r i a l protein in the incubate over 30 min and 5 min reaction times, respectively. Average Km and Vmax values were 14.1 UM and 3.4 p m o l / m i n / m g for the placental preparation and 1.5 ~i and 20.7 p m o l / m i n / m g for the bovine adrenal mitochondrial preparation. In human placenta, the m i t o c h o n d r i a l fraction contained most of the CSCC activity. Inhibition studies showed that a m i n o g l u t e t h i m i d e (500 ~M) inhibited both placental and bovine adrenal activities at the same level (about 80-90 % inhibition) but androstenedione (500 ~M), metyrapone (500 ~ M), benzo(a)pyrene (800 ~M) and E m u l g e n 911 (0.05 %) were more effective in h u m a n placental preparations. Neither of the activities were inhibited to any great extent by ~-n a p h t h o f l a v o n e (500 ~M), SKF 525A (500 ~M) or 7-e t h o x y c o u m a r i n (I mM).
Placenta, 1997
Human placental xenobiotic metabolizing and aromatase activities were measured in placentae at te... more Human placental xenobiotic metabolizing and aromatase activities were measured in placentae at term obtained from pregnancies diagnosed as intrahepatic cholestasis (IC). Compared with controls, several cytochrome P450-dependent (CYP) mono-oxygenases were significantly decreased in IC placentae: 7-ethoxycoumarin O-deethylase by 75 per cent, 7-ethoxyresorufin O-deethylase by 95 per cent, aromatase activity by 37 per cent and androstenedione formation, using testosterone as a substrate, by 20 per cent. These results demonstrate that maternal intrahepatic cholestasis effectively decreases CYP dependent metabolism in human placenta in vitro which may pose a potential risk to the wellbeing of the fetus. Because aromatase activity in IC placentae is significantly lower as compared with healthy controls, safety of the drug therapies which further inhibit aromatase activity are questioned.
Pharmacology & Therapeutics, 1987
Some H2-receptor antagonists can interact with the biotransformation of other drugs. This is due ... more Some H2-receptor antagonists can interact with the biotransformation of other drugs. This is due to their selective binding to the various forms of cytochrome P-450. We tested the in vitro effects (IC50) of 5 different H2-receptor antagonists (Cimetidine (C), Oxmetidine (O), Ranitidine (R), Famotidine (F) and Nizatidine (N)) on aryl hydrocarbon hydroxylase (AHH), 7-ethoxycoumarin-O-deethylase ~CDE) and 7-ethoxyresorufin-Odeethylase (ERDE) activities using microsomes from rats. In addition, their binding to human microsomal cytochrome P-450 was evaluated. The in vivo effects of these antagonists were investigated on the hepatic elimination of diazepam in healthy human volunteers. O was found to be the most effective inhibitor (IC50=0.1 to 0.3m~) of the enzyme activities studied. C also showed a clear inhibitory effect (IC50 = 0.4 to 0.7 re_M) whereas the remaining drugs were more than 10 times less potent. Likewise, when diazepam was used as a substrate, microsomal conversion to desmethyldiazepam and temazepam was inhibited by oxmetidine (ICs0 = 0.02 mu). The binding effects of these antagonists showed the same tendency. However, only C had a clear inhibitory effect on the elimination of diazepam while R,O,N and F did not affect the pharmacokinetics of diazepam. Thus, it could be concluded from our structure/activity relationship studies that one cannot extrapolate, in every case, in vitro data to the inhibitory potency of H2-receptor antagonists on human drug metabolism.
Human & Experimental Toxicology, 1996
1 Rat hepatic cytochrome P450s induced by dipyrone were studied enzymatically, immunochemically a... more 1 Rat hepatic cytochrome P450s induced by dipyrone were studied enzymatically, immunochemically and immunohistochemically. 2 Dipyrone administered to male Wistar rats increased pentoxyresorufin O-depentylation (PROD), ethoxyresor ufin O-deethylation (EROD) and 7-ethoxycoumarin O- deethylation (ECOD) activities up to 44-, 1.9-, and 2.6-fold, respectively. Aryl hydrocarbon hydroxylase (AHH) activ ity was not affected. 3 Immunoinhibition with the monoclonal antibody (Mab) 2-66-3 (to CYP2B1/2) markedly decreased PROD and EROD activities, but not AHH activity. The Mab 1-7-1 (to CYP1A1/2) was without effect. 4 Histochemically, the Mab 2-66-3 gave a strong and uniform staining in livers from dipyrone-treated rats, whereas the Mab 1-7-1 gave a positive reaction in a narrow perivenous strip. 5 The induction pattern as well as inhibition by the Mabs convincingly demonstrate the predominant production of CYP2B1/2 in the induction spectrum of dipyrone. The increase in enzyme activities other th...
Biochemical Pharmacology, Feb 1, 1996
The expression of individual xenobiotic-metabolizing cytochrome P450 (CYP) genes in human placent... more The expression of individual xenobiotic-metabolizing cytochrome P450 (CYP) genes in human placenta was studied at the mRNA level by reverse transcriptase-polymerase chain reaction (RT-PCR). mRNAs of CYP1A1, CYP2E1, CYP2F1, CYP3A3/4, CYP3A5, and CYP4B1 were detected by RT-PCR, and CYP1A2, CYP2A6/7, CYP2B6/7, CYp2C8-19, CYP2D6, and CYp3A7 were not detected. Several enzyme activity assays and immunoblasts were used to further characterize expression of forms producing detectable mRNA transcripts. The catalytic activities of 7-ethoxycoumarin O-deethylase (ECOD), 7-ethoxyresorufin O-deethylase (EROD) and aryl hydrocarbon hydroxylase (AHH) were substantially increased in response to maternal cigarette smoking, and paralleled the amount of CYP1A1 mRNA and protein. Aromatase activities were slightly lower in placentas exposed to cigarette smoke compared with nonexposed placentas. These data show that several xenobiotic-metabolizing CYP genes are expressed in human placenta at a low level. The significant of such low-level expression is unknown, but it may have local physiological or toxic consequences.
South African Journal of Botany, Mar 1, 2018
the extraction techniques of the white flowering Nerium oleander L. (Apocynaceae) and commercial ... more the extraction techniques of the white flowering Nerium oleander L. (Apocynaceae) and commercial feeds. Organic (hexane, acetone and methanol) sequential and aqueous (infusion and decoction) extractions were explored. Subsequently, a qualitative and HPLC quantitative analysis was carried out to compare contents of ANFs where the Mann Whitney U statistical tool was used at a threshold level of 0.05. The results showed higher extraction yields in all aqueous extractions. Therefore, an infusion may be considered as the best approach to mitigate plant poisoning due by ANFs in plants since it proved to be an efficient, safe and reliable method. Furthermore, although the results were not so significant (p b 0.05), a high saponin content of 0.113 ± 0.104 mg/g in diosgenin equivalent was obtained in commercial feeds. In addition, LC-MS will be conducted to characterise the quantified ANFs from the sample.
Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
A comprehensive set of 3-phenylcoumarin analogues with polar substituents was synthesised for blo... more A comprehensive set of 3-phenylcoumarin analogues with polar substituents was synthesised for blocking oestradiol synthesis by 17-b-hydroxysteroid dehydrogenase 1 (HSD1) in the latter part of the sulphatase pathway. Five analogues produced !62% HSD1 inhibition at 5 mM and, furthermore, three of them produced !68% inhibition at 1 mM. A docking-based structure-activity relationship analysis was done to determine the molecular basis of the inhibition and the cross-reactivity of the analogues was tested against oestrogen receptor, aromatase, cytochrome P450 1A2, and monoamine oxidases. Most of the analogues are only modestly active with 17-b-hydroxysteroid dehydrogenase 2a requirement for lowering effective oestradiol levels in vivo. Moreover, the analysis led to the synthesis and discovery of 3-imidazolecoumarin as a potent aromatase inhibitor. In short, coumarin core can be tailored with specific ring and polar moiety substitutions to block either the sulphatase pathway or the aromatase pathway for treating breast cancer and endometriosis.
Reproductive Toxicology, 2021
Journal of Psychiatric Research, 2021
Alternatives to Laboratory Animals, 2005
European Journal of Cancer and Clinical Oncology, 1987
Biochemical Journal, 2016
Polyamine metabolism is an attractive anticancer drug target, since polyamines are absolutely req... more Polyamine metabolism is an attractive anticancer drug target, since polyamines are absolutely required for cellular proliferation, and increased levels of polyamines and their biosynthetic enzyme ornithine decarboxylase (ODC) are associated with cancer. Triethylenetetramine (TETA) is a charge-deficient isosteric analogue of the polyamine spermidine (Spd) and a Cu(II)-chelating compound used for the treatment of Wilson's disease, and it has been implicated as a potential anticancer therapeutic drug. In the present study, we studied the effects of TETA in comparison with two other Cu(II)-chelators, D-penicillamine (PA) and tetrathiomolybdate (TTM), on polyamine metabolism in DU145 prostate carcinoma, MCF-7 breast carcinoma and JEG-3 choriocarcinoma cells. TETA induced antizyme, down-regulated ODC and inhibited [14C] Spd uptake. Moreover, it completely prevented α-difluoromethylornithine (DFMO)-induced increase in [14C] Spd uptake, and inhibited [14C] putrescine (Put) uptake and OD...
Monografias De La Real Academia Nacional De Farmacia, 2004
La seleccion de especies animales optimas que puedan servir para estudiar el metabolismo de farma... more La seleccion de especies animales optimas que puedan servir para estudiar el metabolismo de farmacos en humanos es todavia un gran reto en el programa de desarrollo de farmacos. Las especies utilizadas en estudios de metabolismo deberian tambien incluir parametros de toxicidad relacionados con el metabolismo. El uso de proteinas CYP recombinantes humanas y de sistemas de expresion no puede resolver este problema. Las especies mas usadas en estudios metabolicos son: raton, rata, conejo, perro y mono, y en menor grado cobayas y hamsters. Todos ellos son de alguna manera defectivos en su perfil de CYP cuando se comparan al humano. Por ejemplo, la presencia del enzima CYP1A2 en mono es controvertida; las actividades marcadoras clasicas de los CYP2C y CYP2E en perro estan cuestionadas; el CYP2A de higado de rata no cataliza la reaccion de la 7-hidroxilacion de la cumarina; la CYP2D de cerdo no cataliza la reaccion de la hidroxilacion de la debrisoquina y diversas otras formas CYP tienen pesos moleculares diferentes a los CYP humanos o de rata. Excepto en el hombre y la rata, las proporciones relativas de diversas formas CYP a nivel basal no han sido investigadas y cuantificadas en otras especies. Aunque los primates no humanos se han considerado el mejor modelo para estudiar el metabolismo de farmacos en humanos, debido a rezones eticas el uso de monos puede no ser la primera opcion para el estudio in vivo de las caracteristicas metabolicas de una nueva entidad quimica. Debido a las diferencias dependientes de las especies en la estructura primaria de las distintas formas CYP y en la expresion genica que conduce las cascadas reguladoras, pueden encontrarse notables diferencias en el nivel basal de la expresion de CYP en su inducibilidad y en las propiedades de union a sustratos, inhibidores y anticuerpos. Por tanto, el principal obstaculo en la interpretacion de los resultados asociados a CYP de una especie a otra es la carencia de conocimientos basicos necesarios para hacer el diagnostico en otras especies.
Translationaalinen lääketutkimus ja -kehitys
Placenta, 2000
We investigated the effects of maternal gestational corticosteroid therapy on placental xenobioti... more We investigated the effects of maternal gestational corticosteroid therapy on placental xenobiotic and steroid metabolizing enzymes at term in 20 glucocorticoid/betamethasone treated (with various doses) and control (n=10) women. A single dose of betamethasone (12 mg i.m. twice at a 24-h interval) was given to 15 mothers at risk of preterm delivery to prevent respiratory syndrome in their premature newborns. Five mothers were treated more than once. The gestation time in mothers receiving the glucocorticoid therapy varied from 22-38 gestational weeks. Compared with controls, a significant decrease in placental aromatase activity (53.6+/-18.0 pmol/mg/min versus 119+/-30 pmol/mg/min, P=0.0007) and placental CYP19 mRNA content (by 50 per cent ) was observed in mothers treated with glucocorticoids. Also the formation of androstenedione (13.2+/-8.1 pmol/mg/min, steroids versus 30.03+/-5.2 pmol/mg/min, controls, P< 0.001), using testosterone as the substrate, and 7-ethoxycoumarin O-deethylase (P< 0.05) and 7-ethoxyresorufin O-deethylase (P< 0.09) were slightly decreased in the glucocorticoid treated compared to control patients' values. The changes were not dependent on the number of treatments or the time between treatment and delivery. Our results demonstrate that even a single dose of glucocorticoid given to expectant mothers is associated with diminished placental steroid hormone and xenobiotic metabolizing enzymes at term. Further studies are needed to assess whether these changes affect the well-being of the fetus and its later development.
Journal of Biochemical Toxicology, 1989
The involvement of cytochrome P-450 isozymes in the activation of benzo[a]pyrene (BP) by human pl... more The involvement of cytochrome P-450 isozymes in the activation of benzo[a]pyrene (BP) by human placental and liver microsomes was studied in vitro using monoclonal antibodies (Mab) toward the major 3-methylcholanthrene (MC)-inducible and phenobarbital-inductible rat liver P-450 isozymes (Mab 1-7-1 and Mab 2-66-3, respectively). Microsomes from human placenta and liver and rat liver were incubated with BP and DNA, and BP-diolepoxide-DNA (BPDE-DNA) adducts were measured by synchronous fluorescence spectrophotometry (SFS). The only BP metabolite giving the same fluorescence peak as chemically modified BPDE-DNA was BP-7,8-dihydrodiol. Five (smokers) out of 29 human placentas (smokers and nonsmokers), and five out of nine human livers were able to metabolically activate BP to BPDE-DNA adducts in this system. The Mab 1-7-1 totally inhibited the formation of BPDE-DNA adducts in placental microsomal incubations. Inhibition using rat or human liver microsomes was 50-60% and about 90%, respectively. The Mab 2-66-3 had no effect in any of the microsome types. Adduct formation was inhibited more strongly and at lower concentrations of Mab 1-7-1 compared with the inhibition of AHH activity. This study is a clear indication of the major role of P-450IA1 (P-450c) in human placenta and probably P-450IA2 (P-450d) in human liver in BP activation, while other isozymes also take part in the activation in rat liver. Furthermore, this clearly indicates that AHH activity and BP activation are not necessarily associated.
Biomarkers in Toxicology, 2014
ABSTRACT Nutrient and gas exchange between mother and fetus and production of hormones sustaining... more ABSTRACT Nutrient and gas exchange between mother and fetus and production of hormones sustaining fetal development are important placental functions carried out by a rich selection of transporter proteins and a variety of metabolizing enzymes. The same proteins handle many xenobiotics which in placenta may pass, accumulate, and change placental functions, causing toxicity. Because of structural and functional variation between species, human placental tissue and human trophoblastic cell lines are the most used systems in the search for placental biomarkers of toxicity. They would be helpful in evaluation of drug toxicity in placenta, and in toxicological risk assessment. Only a few exist so far, e.g. changes in CYP19A1/aromatase by hormonally active compounds, metallothioneins in metal exposure, and level of PAH-DNA adducts associated with fetotoxicity. New possibilities are provided, e.g. by the emerging field of placental epigenetics. Use of placenta and placental biomarkers in regulatory toxicology also awaits further data.
Clinical Pharmacology & Therapeutics, 2007
Toxicology Letters, 1994
some cases, not all the responses in single GCTs from the same organ of origin were superimposabl... more some cases, not all the responses in single GCTs from the same organ of origin were superimposable and not all were in accordance with previously published papers.
Steroids, 1984
Cholesterol side-chain cleavage (CSCC) activity towards exogenous cholesterol was quantified by a... more Cholesterol side-chain cleavage (CSCC) activity towards exogenous cholesterol was quantified by an one-step reversed-phase m i n i c o l u m n method for the separation of pregnenolone formed in the reaction. The assay is rapid and reproducible. The method is linear for up to 2 mg of placental m i t o c h o n d r i a l protein and up to I mg of bovine adrenal m i t o c h o n d r i a l protein in the incubate over 30 min and 5 min reaction times, respectively. Average Km and Vmax values were 14.1 UM and 3.4 p m o l / m i n / m g for the placental preparation and 1.5 ~i and 20.7 p m o l / m i n / m g for the bovine adrenal mitochondrial preparation. In human placenta, the m i t o c h o n d r i a l fraction contained most of the CSCC activity. Inhibition studies showed that a m i n o g l u t e t h i m i d e (500 ~M) inhibited both placental and bovine adrenal activities at the same level (about 80-90 % inhibition) but androstenedione (500 ~M), metyrapone (500 ~ M), benzo(a)pyrene (800 ~M) and E m u l g e n 911 (0.05 %) were more effective in h u m a n placental preparations. Neither of the activities were inhibited to any great extent by ~-n a p h t h o f l a v o n e (500 ~M), SKF 525A (500 ~M) or 7-e t h o x y c o u m a r i n (I mM).
Placenta, 1997
Human placental xenobiotic metabolizing and aromatase activities were measured in placentae at te... more Human placental xenobiotic metabolizing and aromatase activities were measured in placentae at term obtained from pregnancies diagnosed as intrahepatic cholestasis (IC). Compared with controls, several cytochrome P450-dependent (CYP) mono-oxygenases were significantly decreased in IC placentae: 7-ethoxycoumarin O-deethylase by 75 per cent, 7-ethoxyresorufin O-deethylase by 95 per cent, aromatase activity by 37 per cent and androstenedione formation, using testosterone as a substrate, by 20 per cent. These results demonstrate that maternal intrahepatic cholestasis effectively decreases CYP dependent metabolism in human placenta in vitro which may pose a potential risk to the wellbeing of the fetus. Because aromatase activity in IC placentae is significantly lower as compared with healthy controls, safety of the drug therapies which further inhibit aromatase activity are questioned.
Pharmacology & Therapeutics, 1987
Some H2-receptor antagonists can interact with the biotransformation of other drugs. This is due ... more Some H2-receptor antagonists can interact with the biotransformation of other drugs. This is due to their selective binding to the various forms of cytochrome P-450. We tested the in vitro effects (IC50) of 5 different H2-receptor antagonists (Cimetidine (C), Oxmetidine (O), Ranitidine (R), Famotidine (F) and Nizatidine (N)) on aryl hydrocarbon hydroxylase (AHH), 7-ethoxycoumarin-O-deethylase ~CDE) and 7-ethoxyresorufin-Odeethylase (ERDE) activities using microsomes from rats. In addition, their binding to human microsomal cytochrome P-450 was evaluated. The in vivo effects of these antagonists were investigated on the hepatic elimination of diazepam in healthy human volunteers. O was found to be the most effective inhibitor (IC50=0.1 to 0.3m~) of the enzyme activities studied. C also showed a clear inhibitory effect (IC50 = 0.4 to 0.7 re_M) whereas the remaining drugs were more than 10 times less potent. Likewise, when diazepam was used as a substrate, microsomal conversion to desmethyldiazepam and temazepam was inhibited by oxmetidine (ICs0 = 0.02 mu). The binding effects of these antagonists showed the same tendency. However, only C had a clear inhibitory effect on the elimination of diazepam while R,O,N and F did not affect the pharmacokinetics of diazepam. Thus, it could be concluded from our structure/activity relationship studies that one cannot extrapolate, in every case, in vitro data to the inhibitory potency of H2-receptor antagonists on human drug metabolism.
Human & Experimental Toxicology, 1996
1 Rat hepatic cytochrome P450s induced by dipyrone were studied enzymatically, immunochemically a... more 1 Rat hepatic cytochrome P450s induced by dipyrone were studied enzymatically, immunochemically and immunohistochemically. 2 Dipyrone administered to male Wistar rats increased pentoxyresorufin O-depentylation (PROD), ethoxyresor ufin O-deethylation (EROD) and 7-ethoxycoumarin O- deethylation (ECOD) activities up to 44-, 1.9-, and 2.6-fold, respectively. Aryl hydrocarbon hydroxylase (AHH) activ ity was not affected. 3 Immunoinhibition with the monoclonal antibody (Mab) 2-66-3 (to CYP2B1/2) markedly decreased PROD and EROD activities, but not AHH activity. The Mab 1-7-1 (to CYP1A1/2) was without effect. 4 Histochemically, the Mab 2-66-3 gave a strong and uniform staining in livers from dipyrone-treated rats, whereas the Mab 1-7-1 gave a positive reaction in a narrow perivenous strip. 5 The induction pattern as well as inhibition by the Mabs convincingly demonstrate the predominant production of CYP2B1/2 in the induction spectrum of dipyrone. The increase in enzyme activities other th...