RESUMO
Osteoporosis is a metabolic bone disorder which increases fragility fracture risk. Elderly individuals, especially postmenopausal women, are particularly susceptible to osteoporosis. Although rare, osteoporosis in children and young adults is becoming increasingly evident, highlighting the need for timely diagnosis, management and follow-up. Early-onset osteoporosis is defined as the presence of a low BMD (Z-score of ≤ -2.0 in individuals aged < 20 years; T-score of ≤ -2.5 in those aged between 20 to 50 years) accompanied by a clinically significant fracture history, or the presence of low-energy vertebral compression fractures even in the absence of osteoporosis. Affected children and young adults should undergo a thorough diagnostic workup, including collection of clinical history, radiography, biochemical investigation and possibly bone biopsy. Once secondary factors and comorbidities are excluded, genetic testing should be considered to determine the possibility of an underlying monogenic cause. Defects in genes related to type I collagen biosynthesis are the commonest contributors of primary osteoporosis, followed by loss-of-function variants in genes encoding key regulatory proteins of canonical WNT signalling (specifically LRP5 and WNT1), the actin-binding plastin-3 protein (encoded by PLS3) resulting in X-linked osteoporosis, and the more recent sphingomyelin synthase 2 (encoded by SGMS2) which is critical for signal transduction affecting sphingomyelin metabolism. Despite these discoveries, genetic causes and underlying mechanisms in early-onset osteoporosis remain largely unknown, and if no causal gene is identified, early-onset osteoporosis is deemed idiopathic. This calls for further research to unravel the molecular mechanisms driving early-onset osteoporosis that consequently will aid in patient management and individualised targeted therapy.
Assuntos
Fraturas por Compressão , Osteoporose , Fraturas da Coluna Vertebral , Criança , Idoso , Humanos , Feminino , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Densidade Óssea/genética , Osteoporose/etiologia , Osteoporose/genética , Via de Sinalização WntRESUMO
Three continuously stirred-tank reactors fed with manure operating under high ammonia levels (5.0 g NH3-N L-1) and with increased organic loading rate (OLR), (2.09 R1, 3.02 R2 and 4.0 R3 g VS L-1 d-1), achieved through glucose amendment in R2 and R3, were inoculated with an ammonia-acclimatized microbial culture. Successful bioaugmentation was endured only in R2 and R3, both reactors characterized by high OLR, resulting in 19.6 and 24.5% increase in methane production, respectively. The high OLRs in these reactors favored the co-occurrence of the hydrogenotrophic (Methanobacteriaceae), methylotrophic (Methanomethylophilaceae) and aceticlastic methanogenic pathways. The latter was supported by the successful establishment of ammonium-tolerant Methanosarcina, prevailing in the inoculum. Oppositely in R1, the low OLR prevented the establishment of Methanosarcina, leading to an exclusive hydrogenotrophic methanogenesis and reduced methane production. HRT shortening resulted in limited effect on biomethane performance, indicating a well establishment of the introduced bioaugmentation culture in the reactors.
RESUMO
Three Continuously Stirred Tank Reactors (CTSRs) were operating at steady state conditions with Organic Loading Rates (OLR) of 2.09, 3.024 and 4.0 g VS L-1 d-1. Glucose was used as the sole factor for increasing the OLR, linking the increase of the OLR with the C/N ratio increase. The reactors were stressed by increasing the ammonia concentration to 5 g L-1 from 1.862 g L-1. The results showed elevating inhibition of the anaerobic process by increasing the C/N ratio just by increasing the OLR, under the high ammonia concentration. A different response of the bacterial and archaeal community under ammonia stressed conditions was also observed. Under the high ammonia concentration, hydrogen-depended methylotrophic was the dominant methanogenesis route at OLR of 2.09 g VS L-1d-1, while the hydrogenotrophic route was the dominant at the high OLR of 4 g VS L-1d-1, which coincided with high acetate and propionate concentrations.
Assuntos
Esterco , Microbiota , Amônia , Anaerobiose , Reatores Biológicos , MetanoRESUMO
PURPOSE OF REVIEW: We summarize recent evidence on the shared genetics within and outside the musculoskeletal system (mostly related to bone density and osteoporosis). RECENT FINDINGS: Osteoporosis is determined by an interplay between multiple genetic and environmental factors. Significant progress has been made regarding its genetic background revealing a number of robustly validated loci and respective pathways. However, pleiotropic factors affecting bone and other tissues are not well understood. The analytical methods proposed to test for potential associations between genetic variants and multiple phenotypes can be applied to bone-related data. A number of recent genetic studies have shown evidence of pleiotropy between bone density and other different phenotypes (traits, conditions, or diseases), within and outside the musculoskeletal system. Power benefits of combining correlated phenotypes, as well as unbiased discovery, make these studies promising. Studies in humans are supported by evidence from animal models. Drug development and repurposing should benefit from the pleiotropic approach. We believe that future studies should take into account shared genetics between the bone and related traits.
Assuntos
Densidade Óssea/genética , Pleiotropia Genética , Osteoporose/genética , Osso e Ossos , Interação Gene-Ambiente , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , FenótipoRESUMO
This paper concerns the statistical distribution of the crest heights associated with surface waves in intermediate water depths. The results of a new laboratory study are presented in which data generated in different experimental facilities are used to establish departures from commonly applied statistical distributions. Specifically, the effects of varying sea-state steepness, effective water depth and directional spread are investigated. Following an extensive validation of the experimental data, including direct comparisons to available field data, it is shown that the nonlinear amplification of crest heights above second-order theory observed in steep deep water sea states is equally appropriate to intermediate water depths. These nonlinear amplifications increase with the sea-state steepness and reduce with the directional spread. While the latter effect is undoubtedly important, the present data confirm that significant amplifications above second order (5-10%) are observed for realistic directional spreads. This is consistent with available field data. With further increases in the sea-state steepness, the dissipative effects of wave breaking act to reduce these nonlinear amplifications. While the competing mechanisms of nonlinear amplification and wave breaking are relevant to a full range of water depths, the relative importance of wave breaking increases as the effective water depth reduces.
Assuntos
Nadadeiras de Animais/crescimento & desenvolvimento , Pesqueiros/métodos , Dourada/fisiologia , Peixe-Zebra/fisiologia , Nadadeiras de Animais/anatomia & histologia , Animais , Larva/anatomia & histologia , Larva/crescimento & desenvolvimento , Larva/fisiologia , Dourada/anatomia & histologia , Dourada/crescimento & desenvolvimento , Temperatura , Peixe-Zebra/anatomia & histologia , Peixe-Zebra/crescimento & desenvolvimentoAssuntos
Tamanho Corporal , Dourada/anatomia & histologia , Animais , Embrião não Mamífero/anatomia & histologia , Embrião não Mamífero/embriologia , Desenvolvimento Embrionário , Pesqueiros , Temperatura Alta , Larva/anatomia & histologia , Larva/crescimento & desenvolvimento , Dourada/embriologia , Dourada/crescimento & desenvolvimentoRESUMO
BACKGROUND: PCOS is presented by a broad spectrum of menstrual irregularities appearing often at puberty or later on during the reproductive years in women suffering from this multifaceted syndrome. To our knowledge, there is no evidence to suggest whether the time of onset of menstrual irregularities (peri or post pubertal) indicates a differential metabolic and/or hormonal profile as well as ovarian ultrasonographic findings, in adulthood in women with PCOS. AIM OF THE STUDY: To compare anthropometric, hormonal-metabolic profile and ultrasound findings in PCOS women with peripubertal onset of menstrual disorders with the corresponding data obtained from PCOS patients with post pubertal onset of menstrual irregularities, matched for BMI and age. PATIENTS-METHODS: 89 PCOS women were evaluated cross-sectionally at the age of 25 years. In 49 subjects menstrual irregularities were present from menarche, whereas in 40 women the irregularities appeared at least 3 years post menarche. RESULTS: Anthropometric parameters were comparable between the 2 groups. The 2 groups did not differ on metabolic and hormonal profile as well as ovarian ultrasound findings. CONCLUSIONS: These data indicate that the timing of menstrual irregularities, do not appear to have an impact, on hormonal/metabolic profile and ovarian ultrasound morphology in patients diagnosed with PCOS, later in life.
Assuntos
Distúrbios Menstruais/epidemiologia , Distúrbios Menstruais/etiologia , Síndrome do Ovário Policístico/complicações , Adulto , Idade de Início , Estudos de Casos e Controles , Estudos Transversais , Feminino , Hormônios Esteroides Gonadais/sangue , Gonadotropinas/sangue , Humanos , Resistência à Insulina/fisiologia , Lipídeos/sangue , Distúrbios Menstruais/sangue , Síndrome do Ovário Policístico/sangue , Síndrome do Ovário Policístico/epidemiologia , Fatores de Tempo , Adulto JovemRESUMO
Pleurotus ostreatus grown in bioreactor batch cultures in a model phenolic wastewater (diluted and sterilized olive oil mill wastewater-OMW), caused significant phenolic removal. Laccase, the sole ligninolytic enzyme detected in the growth environment, was produced during primary metabolic growth. The bioprocess was simulated with the aid of a mathematical model and the parameters of growth were determined. When the fungal biomass was increased in the reactor (during repeated batch experiments) the rate of reducing sugars consumption progressively increased, but a phenolic fraction seemed of being strongly resistant to oxidation. The toxicity of OMW against the seeds of Lepidium sativum and the marine Branchiopoda Artemia sp. was significantly decreased after biotreatment. On the contrary, the toxicity against the freshwater Branchiopoda Daphnia magna was not affected by the treatment, whereas on the soil and freshwater sediments Ostracoda Heterocypris incongruens was slightly decreased. Both treated and untreated OMWs, used as water for irrigation of lettuce and tomato plants, did not significantly affect the uptake of several nutrients by the cultivated plants, but resulted in a decrease in the plant yields, which was minimized when high OMW dilutions were used. As a conclusion, P. ostreatus is able to reduce phenolic content and toxicity of sterilized OMW, in bioreactor cultures. However, high OMW dilutions should be used, and/or additional treatment should be applied before use of the OMW in the environment, e.g. as water for irrigation. Further research should be done in order to transfer this technology under industrial conditions (e.g. by using unsterilized OMW).
Assuntos
Reatores Biológicos , Modelos Teóricos , Fenóis/metabolismo , Fenóis/toxicidade , Pleurotus/enzimologia , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade , Purificação da Água/métodos , Animais , Artemia , Crustáceos , Resíduos Industriais , Lacase/farmacologia , Oxirredução , Fenóis/isolamento & purificação , Testes de Toxicidade , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
The soil sampling guidelines used in European countries (ESSG), as kindly provided by the national institutions which participated in the project, have been recorded, studied, evaluated and presented in this paper. The aim has been to ascertain what soil sampling guidelines exist in Europe; to detect similarities and differences (comparable results), advantages and deficiencies; to identify incompatible strategies and evaluate how methodologies might affect data quality; to investigate sources of deviations or uncertainties; to improve comparability and representativeness of soil sampling; to investigate the need for harmonised sampling guidelines; and to develop suggestions for standard operating procedures (SOP). Soil sampling guidelines throughout Europe differ as to whether they are applied by law, or used throughout the country. In some countries these are ISO/DIS related or based (ISO 10381-1, 1995; ISO 10381-2, 1995), or are produced by a scientific society or a standardisation body. As far as sampling strategy is concerned, not all sampling guidelines clearly describe the sampling scale, the specifications for contamination risk precautions, the sampling plan and protocol structure and the pre-analysis treatment of the soil samples. The purpose for sampling, in descending order of frequency, is soil pollution, soil fertilisation, general soil monitoring, background risk assessment, or else it is not specified. The majority of countries do not sample the top organic matter separately. Sampling depth is either related to the morphogenetic horizon or to ad hoc sampling depth, which is not specified in all cases. They suggest mass- and volume-related soil sampling, while the sampling pattern is not presented in all national guidelines. The criteria for area, site, unit, sub-unit, and point selection are mainly based on pedology and land use, following the history and pre-screening information or geology, or is site related. Some guidelines suggest the division of sampling units into sub-units. The sampling pattern is mainly grid sampling, grid and random sampling, or not mentioned. Sampling density inside the sampling unit either varies greatly or it is not mentioned, while the size of the sampling unit varies widely. Most guidelines require the collection of composite instead of simple samples, while some prefer sampling soil profiles. In the European SSG many technical details and steps are either not defined or vary, while in the pre-analysis treatment quality assurance (QA) and quality control (QC) approaches are used either both in the lab and in the field, or only in the field, or are not mentioned. The common points and the points in which harmonisation could be started or achieved are discussed.
Assuntos
Monitoramento Ambiental/métodos , Poluentes do Solo/análise , Agricultura , Europa (Continente) , Guias como Assunto , Cooperação Internacional , Controle de Qualidade , Medição de RiscoRESUMO
Fifteen institutions from 13 European countries and Switzerland participated in a comparative test sampling at the Dornach site, near Basel in Switzerland. They received the site description and were asked to develop their own sampling plans, based on their national guidelines for a three-dimensional description of the Pb, Zn, Cu and Cd pollution, with a maximum of 15 samples. The comparative sampling test took place in late August 1997. The sampling plans and records, provided by the participants, were compared and evaluated in terms of sampling strategy throughout the site, the sampling strategy inside the sampling unit, strategy at the sampling point and last minute alteration of the sampling plans in the field. The object of this was to define the similarities and the differences in the sampling plans and identify the crucial steps inducing error or uncertainty which should be harmonized throughout Europe. The number of the total composite samples varied from 4 to 16, while the number of sampling points varied from 4 to 224 and the sampling density varied from 0.25 to 16 single samples per 100 m2. The number of 10 x 10 m2 quadrats from which samples were taken varied from 3 to 56, out of the total 61. The number of sampling units varied between 3 and 12. The criteria in descending order of frequency were: both land use and pedology, land use, pedology. The majority of the national participants divided the sampling units into two or three sub-units, while seven participants collected replicate composite samples from the same sampling unit. Only one sampled from the existing profiles, eight national representatives ignored the plough depth. The sampling pattern inside the sampling unit was in descending order of frequency: random, point sampling, regular, 'W' and 'X' shaped sampling. The number of single samples in the composite varied from 1 to 20. Most of the national participants sampled to pre-defined (ad-hoc) sampling depths, while others sampled soil horizons and others both. The maximum soil depth sampled also varied from 20 to 117 cm. Most participants mixed in the top organic matter horizon while others sampled it separately. Most sampled separately the top Ah horizon in the forest while the rest mixed it with the underlying soil horizon. The last-minute sampling plan alterations were in: the sampling depth (nine), the movement of sampling points (five), the reduction of sub-samples in the composite sample (four), changes in the number of sampling units (three), ignoring the bottom sample (three), not sampling the L/H layer (three) although this was planned, unplanned sampling of the L/H layer (two) and changing the number of planned samples (two). This study has highlighted the need for soil sampling harmonization throughout Europe for pollution and soil quality determination.
Assuntos
Monitoramento Ambiental/métodos , Metais Pesados/análise , Poluentes do Solo/análise , Controle de Qualidade , Projetos de Pesquisa , Manejo de Espécimes , SuíçaRESUMO
Land-use planning with respect to major accident hazards is one of the new requirements of the 'Seveso II Directive'. On top of this requirement, but also recognising the importance of the issue for the control of major accidents, the various European Member States have developed or are developing adequate procedures, approaches and criteria for the acceptability of hazards or risk. At a national level, various criteria are in use based either on 'generic distances', or on the level of consequences, or on the level of risk. At a regional and local level, however, local particularities and the presence of multiple and usually conflicting objectives - such as reduction of risk with simultaneous increase of the benefit from exploitation of land - seem to be of great importance in decision making. The paper focuses especially on the local level and it presents a methodological framework to take these conflicting objectives into account. Furthermore, it discusses the application of this methodology in an interesting case study and it demonstrates the useful insights and the substantial aid with which local planners can be provided.
Assuntos
Resíduos Perigosos/legislação & jurisprudência , Medição de Risco/métodos , Algoritmos , Tomada de Decisões , União Europeia , Medição de Risco/estatística & dados numéricosRESUMO
The paper discusses the use of modern information technologies, and in particular geographic information systems (GIS), in the management and control of major accident risk. For this purpose, the regulatory framework of the recent "Seveso II" Directive is briefly described. This asks for more transparent procedures and decision-making, and requires consultation of the public in land-use and off-site emergency planning. Correspondingly, new demands are put to support tools being developed. The main features of tools dealing with hazard sources mapping, risk assessment, risk management, and emergency planning are discussed and examples are given. Moreover, it is argued that, if appropriately designed, their use can enhance the dialog between plant operators, authorities and the public to facilitate a consensus on risk issues. Finally, limitations in the use of these tools and prospects for future developments are discussed.
Assuntos
Acidentes de Trabalho/estatística & dados numéricos , Geografia , Sistemas de Informação , Medição de Risco/métodos , Gestão da Segurança/métodos , União Europeia , Substâncias PerigosasRESUMO
A methodology for characterizing alternative trajectories of a new highway in the neighborhood of an oil-refinery with respect to the risk to public health is presented. The approach is based on a quantitative assessment of the risk that the storage facilities of flammable materials of the refinery pose to the users of the highway. Physical phenomena with a potential for detrimental consequences to public health such as BLEVE (Boiling Liquid Expanding Vapor Explosion), Unconfined Vapor Cloud Explosion, flash fire and pool fire are considered. Methodological and procedural steps for assessing the individual risk around the tank farm of the oil-refinery are presented. Based on the individual risk, group risk for each alternative highway trajectory is determined.
Assuntos
Indústrias Extrativas e de Processamento , Substâncias Perigosas/efeitos adversos , Óleos Industriais/efeitos adversos , Medição de Risco/métodos , Gestão da Segurança/métodos , Meios de Transporte/normas , Técnicas de Apoio para a Decisão , Explosões/estatística & dados numéricos , Incêndios/estatística & dados numéricos , Humanos , Técnicas de Planejamento , Saúde Pública , Fatores de Risco , VentoRESUMO
Land-Use Planning with respect to major accident hazards constitutes one of the new requirements of the 'Seveso II Directive'. The paper discusses the rationale and the requirements set by the Directive for the operators of the plants and the planning authorities to take into account the major accident hazards in the land-use planning procedure. Then, the paper focuses on approaches and criteria applied in the European Union, and gives information on procedures in other countries, wherever available. The approaches analysed are grouped into three broad categories, namely, establishing 'generic distances', 'consequence based', and 'risk based'. Finally, two illustrative examples facilitate understanding and comparison of the analysed approaches.
Assuntos
Acidentes de Trabalho/prevenção & controle , Planejamento em Desastres/organização & administração , Resíduos Perigosos/prevenção & controle , Gestão da Segurança/organização & administração , União Europeia , Guias como Assunto , Humanos , Medição de RiscoRESUMO
The effects of co-treatment of C3H10T1/2 (10T1/2) cells with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 12-O-tetradecanoylphorbol-13-acetate (TPA) on the expression of the novel cytochrome P4501B1 (CYP1B1) were investigated. As monitored by CYP1B1-catalyzed 7,12-dimethylbenzanthracene (DMBA) metabolism, TPA suppressed basal and TCDD-induced DMBA metabolism in a concentration-dependent manner, with a maximum inhibitory concentration of 100 nM. The suppression of CYP1B1 catalytic activity occurred at two time points during which protein kinase C (PKC) was activated and down-regulated in these cells as judged by analyses of cellular PKC content and PKC-inhibitor (chelerythrine chloride)-influenced suppression of CYP1B1 catalytic activity. Experiments in which TCDD and benzanthracene (BA)-induced DMBA metabolism were monitored in PKCbeta1-overexpressing 10T1/2 cells revealed that the suppression of CYP1B1 activity is a consequence of cellular PKC elevation. This suppression phenomenon could be accounted for by PKC-mediated suppression of TCDD-induced CYP1B1 mRNA and apoprotein and of nuclear translocation of the Ah-receptor. In contrast, the mitogen-activated protein kinase (MAPK) proteins ERKs 1 and 2 were stimulated by TCDD under conditions in which PKC was activated. Collectively, our results suggest that PKC participates in the regulation of CYP1B1 in 10T1/2 cells, positively by directly suppressing the Ah-receptor signaling pathway, followed by an indirect or negative activation of the MAPK signaling pathway.
Assuntos
Hidrocarboneto de Aril Hidroxilases , Sistema Enzimático do Citocromo P-450/biossíntese , Proteína Quinase C/fisiologia , 9,10-Dimetil-1,2-benzantraceno/metabolismo , Alcaloides , Animais , Benzofenantridinas , Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Células Cultivadas , Citocromo P-450 CYP1B1 , Sistema Enzimático do Citocromo P-450/genética , Embrião de Mamíferos , Ativação Enzimática , Indução Enzimática , Regulação da Expressão Gênica , Camundongos , Camundongos Endogâmicos C3H , Fenantridinas , Dibenzodioxinas Policloradas , Proteína Quinase C/antagonistas & inibidores , RNA Mensageiro/análise , Acetato de TetradecanoilforbolRESUMO
The rat CYP2B gene subfamily includes CYP2B1, CYP2B2 and CYP2B3. Translation of an alternatively spliced hepatic CYP2B2 mRNA would generate a CYP2B2 variant, CYP2B2v, having eight additional amino acid residues inserted between CYP2B2 positions 274 and 275. The presence of CYP2B3 and CYP2B2v in rat liver has yet to be demonstrated. cDNA expression vectors were obtained for CYP2B1, CYP2B2, CYP2B3 and CYP2B2v. All four proteins react with an anti-CYP2B1 antibody and can be resolved by SDS-PAGE. A CYP2B3-specific polyclonal antibody raised against an undecapeptide (SPVDPNTIDMT) from near the C-terminus of CYP2B3 detected a constitutive protein on immunoblots of rat liver microsomes, thus demonstrating that the CYP2B3 mRNA is translated in the liver. Similarly, a CYP2B2v-specific polyclonal antibody was raised against a peptide containing the eight additional amino acid residues (VSPAWMRE) predicted to be present in the CYP2B2v protein. It detected a phenobarbital- and Aroclor 1254-inducible protein in rat liver microsomes. Microsomes of Ad293 cells expressing cDNAs for CYP2B2 and CYP2B2v were used to metabolize 7,12-dimethylbenz[a]anthracene (DMBA), and the metabolites produced were compared with those generated by microsomes of cells expressing CYP2B1 cDNA. CYP2B2v had activity similar to that of CYP2B2 for DMBA metabolism. Both CYP2B2 forms preferentially catalyzed 12-hydroxylation, whereas CYP2B1 preferred 7-hydroxylation and exhibited turnover that was strongly suppressed as previously reported. These results demonstrate the existence in rat liver of two new CYP2B proteins: CYP2B3, the major constitutive CYP2B form, and CYP2B2v, which represents a rare case of non-aberrant alternative splicing among xenobiotic-metabolizing P450s.
Assuntos
Hidrocarboneto de Aril Hidroxilases , Sistema Enzimático do Citocromo P-450/genética , Sistema Enzimático do Citocromo P-450/metabolismo , Microssomos Hepáticos/enzimologia , 9,10-Dimetil-1,2-benzantraceno/metabolismo , Processamento Alternativo , Animais , Anticorpos , Sequência de Bases , Linhagem Celular , Citocromo P-450 CYP2B1/genética , Citocromo P-450 CYP2B1/metabolismo , Sistema Enzimático do Citocromo P-450/imunologia , Família 2 do Citocromo P450 , Primers do DNA/genética , Indução Enzimática/efeitos dos fármacos , Humanos , Microssomos Hepáticos/efeitos dos fármacos , Fenobarbital/farmacologia , Polimorfismo Genético , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Distribuição Tecidual , TransfecçãoRESUMO
Cultured rat mammary cells express both CYP1A1 and CYP1B1 in response to polycyclic aromatic hydrocarbons (PAH) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in a cell type-specific manner. The expression of each P450 was determined functionally (regioselective PAH metabolism), as apoprotein (immunoblots) and as mRNA (Northern hybridization). The epithelial rat mammary cells (RMEC) expressed CYP1A1, however only after PAH or TCDD treatment. CYP1B1 protein was scarcely detected in these induced RMEC but was surprisingly active as a participant in 7,12-dimethylbenz[a]anthracene (DMBA) metabolism shown through selective antibody inhibition (40% of total activity). CYP1B1 was selectively expressed in the stromal fibroblast population of rat mammary cells to the exclusion of CYP1A1. In the rat mammary fibroblasts (RMF), CYP1B1 protein and associated activity were each present at low levels constitutively and were highly induced by benz[a]anthracene (BA) to a greater extent than by TCDD (12- versus 6-fold). However, BA (10 microM) and TCDD (10 nM) stimulated the 5.2-kb CYP1B1-specific mRNA equally. These increases are consistent with the involvement of the aryl hydrocarbon (Ah) receptor in the transcription of the CYP1B1 gene and with the additional stabilization of CYP1B1 protein by BA, previously observed in embryo fibroblasts. Exactly this regulation of CYP1B1-dependent activity was seen in RMEC suggesting that this arises from exceptionally active CYP1B1 in a small proportion (5%) of residual RMF. The constitutive expression and PAH inducibility of CYP1B1 and CYP1A1 proteins in RMF and RMEC, respectively, were each substantially decreased (approximately 75%) by a hormonal mixture (17 beta-estradiol (0.2 microM) progesterone (1.5 microM) cortisol (1.5 microM) and prolactin (5 micrograms/ml)). Progesterone and cortisol, added singly to RMF suppressed CYP1B1 protein expression (approximately 80%) in both untreated and BA-induced cells, while cortisol also suppressed the 5.2-kb CYP1B1 mRNA. In contrast, 17 beta-estradiol stimulated constitutive expression of CYP1B1 protein (50-75%) and mRNA level (2- to 3-fold), but did not affect CYP1B1 expression in BA-treated RMF. The expression of CYP1A1 and CYP1B1 is therefore highly cell specific even though each is regulated through the Ah receptor. Each P450 exhibits a surprisingly similar pattern of hormonal regulation even though expressed in different cell types.
Assuntos
Hidrocarboneto de Aril Hidroxilases , Sistema Enzimático do Citocromo P-450/metabolismo , Hormônios/farmacologia , Glândulas Mamárias Animais/efeitos dos fármacos , Glândulas Mamárias Animais/enzimologia , Hidrocarbonetos Policíclicos Aromáticos/farmacologia , 9,10-Dimetil-1,2-benzantraceno/metabolismo , Animais , Benzo(a)Antracenos/farmacologia , Citocromo P-450 CYP1B1 , Sistema Enzimático do Citocromo P-450/genética , Epitélio/enzimologia , Estradiol/farmacologia , Feminino , Fibroblastos/enzimologia , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hidrocortisona/farmacologia , Técnicas In Vitro , Glândulas Mamárias Animais/citologia , Dibenzodioxinas Policloradas/farmacologia , Progesterona/farmacologia , Prolactina/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
Rates of microsomal 17 beta-estradiol (E2) hydroxylation at the C-2, -4, -6 alpha, and -15 alpha positions are each induced greater than 10-fold by treating MCF-7 breast cancer cells with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The TCDD-induced activities at the C-2, -6 alpha and -15 alpha positions have been attributed to cytochrome P450 1A1 (CYP1A1); however, the low Km 4-hydroxylase induced by TCDD appears to be a distinct enzyme. We report here that antibodies to cytochrome P450-EF (mouse CYP1B1) selectivity inhibited the C-4 hydroxylation of E2 catalyzed by microsomes from TCDD-treated MCF-7 cells. Western blots probed with anti-CYP1B antibodies showed the induction of a 52 kDa microsomal protein in response to treatment with TCDD in MCF-7 cells. Western blots of microsomes from HepG2 cells did not show the TCDD-induced 52 kDa protein, and microsomes from TCDD-treated HepG2 cells did not catalyze a low Km hydroxylation of E2 at C-4. Cellular metabolism experiments also showed induction of both the C-2 and -4 hydroxylation pathways in TCDD-treated MCF-7 cells as evidenced by elevated 2- and 4-methoxyestradiol (MeOE2) formation. In contrast, TCDD-treated HepG2 cells showed 2-MeOE2 formation predominantly over 4-MeOE2. Northern blots of RNA isolated from untreated and TCDD-treated cells, when probed with the human CYP1B1 cDNA, showed induction of a 5.2 kb RNA in MCF-7 cells but not in HepG2 cells in response to treatment with TCDD. These results provide additional evidence for the induction by TCDD of a novel E2 4-hydroxylase in MCF-7 cells but not in HepG2 cells and indicate possible endocrine regulatory roles for the newly discovered group of enzymes of the CYP1B subfamily.