RESUMO
The medium-term multiorgan initiation-promotion chemical bioassay (diethylnitrosamine, methyl-nitrosourea, butyl-hydroxybutylnitrosamine, dihydroxypropylnitrosamine, dimethylhydrazine [DMBDD]) with the Fischer 344 rat was proposed as an alternative to the conventional 2-year carcinogenesis bioassay for regulatory purposes. The acronym DMBDD stands for the names of five genotoxic agents used for initiation of multiorgan carcinogenesis. The Brazilian Agency for the Environment officially recognized a variation of this assay (DMBDDb) as a valid method to assess the carcinogenic potential of agrochemicals. Different from the original protocol, this DMBDDb is 30-week long, uses Wistar rats and two positive control groups exposed to carcinogenesis promoters sodium phenobarbital (PB) or 2-acetylaminofluorene (2-AAF). This report presents the experience of an academic laboratory with the DMBDDb assay and contributes to the establishment of this alternative DMBDD bioassay in a different rat strain. Frequent lesions observed in positive groups to evaluate the promoting potential of pesticides and the immunohistochemical expressions of liver cytochrome P450 (CYP) 2B1/2B2 and CYP1A2 enzymes were assessed. Commonly affected organs were liver, kidney, intestines, urinary bladder, and thyroid. PB promoting activity was less evident than that of 2-AAF, especially in males. This study provides a repository of characteristic lesions occurring in positive control animals submitted to a modified alternative 2-stage multiorgan protocol for carcinogenesis in Wistar rat.
Assuntos
2-Acetilaminofluoreno/toxicidade , Testes de Carcinogenicidade/métodos , Carcinógenos/toxicidade , Neoplasias Experimentais/induzido quimicamente , Fenobarbital/toxicidade , Lesões Pré-Cancerosas/induzido quimicamente , Animais , Hidrocarboneto de Aril Hidroxilases/biossíntese , Bioensaio , Citocromo P-450 CYP1A2/biossíntese , Citocromo P-450 CYP2B1/biossíntese , Feminino , Fígado/efeitos dos fármacos , Fígado/enzimologia , Fígado/patologia , Masculino , Neoplasias Experimentais/enzimologia , Tamanho do Órgão/efeitos dos fármacos , Especificidade de Órgãos , Lesões Pré-Cancerosas/enzimologia , Ratos Wistar , Esteroide Hidroxilases/biossínteseRESUMO
Interdisciplinary collaboration is widely recognized and considered essential for optimizing the development of knowledge and practice. However, interdisciplinarity is commonly accepted as an unquestioned good; rarely examined as both a source of benefit as well as difficulty for nursing and other disciplines. The aim of this article is to critically examine the opportunities and challenges that interdisciplinarity can provide for research in nursing and other disciplines. Based on a North American perspective, I describe the emergence of uni-disciplinary nursing research and the knowledge exchanges that occurred between nursing and other disciplines. I discuss the rise of interdisciplinary research, outline several examples of nursing participation in interdisciplinarity, and highlight the prominent benefits and difficulties associated with interdisciplinary research. I argue that authentic collaboration is required to conduct meaningful interdisciplinary research and describe how this can be promoted.
Colaboração interdisciplinar é amplamente reconhecida e considerada essencial para a otimização do desenvolvimento do conhecimento e prática. No entanto, a interdisciplinaridade é comumente aceita como um bem inquestionável, raramente examinado tanto como uma fonte de benefícios, bem como dificuldade para a enfermagem e outras disciplinas. O objetivo deste artigo é analisar criticamente as oportunidades e desafios que a interdisciplinaridade pode oferecer para a pesquisa em enfermagem e outras disciplinas. Com base em uma perspectiva norte-americana, descreve-se o surgimento de pesquisas em enfermagem unidisciplinar e as trocas de conhecimento que ocorreram entre a enfermagem e outras disciplinas. Discute-se a ascensão da pesquisa interdisciplinar, delineiam-se vários exemplos de participação da enfermagem na interdisciplinaridade, e destacam-se os benefícios proeminentes e dificuldades associadas com a pesquisa interdisciplinar. Defende-se que a colaboração autêntica é necessária para conduzir a pesquisa interdisciplinar significativa e descreve-se como isso pode ser promovido.
La colaboración interdisciplinaria es ampliamente reconocida y considerada esencial para optimizar el desarrollo del conocimiento y la práctica. Sin embargo, la interdisciplinariedad es comúnmente aceptada como un bien incuestionable; rara vez examinada tanto como una fuente de beneficio, así como de dificultad para la enfermería y otras disciplinas. El objetivo de este artículo es examinar críticamente las oportunidades y desafíos que la interdisciplinariedad puede proporcionar para la investigación en enfermería y otras disciplinas. Sobre la base de una perspectiva norteamericana, describe-se el surgimiento de la investigación en enfermería unidisciplinaria y los intercambios de conocimientos que se produjeron entre la enfermería y otras disciplinas. Se discute el aumento de la investigación interdisciplinaria, esbozan-se varios ejemplos de la participación de enfermería en la interdisciplinariedad, y destacan-se los beneficios y las dificultades asociadas con la investigación interdisciplinaria. Argumenta-sé que se requiere auténtica colaboración para llevar a cabo la investigación interdisciplinaria significativa y describe-se la forma en que esto puede ser promovido. .
Assuntos
Humanos , Feminino , Catecol O-Metiltransferase/biossíntese , /biossíntese , Placenta/enzimologia , Gravidez/metabolismo , Esteroide Hidroxilases/biossíntese , Xenobióticos/farmacologia , Hidroxianisol Butilado/farmacologia , Carcinógenos , Cumarínicos/farmacologia , Indução Enzimática , Naftóis/farmacologia , Primeiro Trimestre da GravidezRESUMO
In order to better understand vitamin D3 in cattle metabolism, we quantified 1alpha-HYD and 24-HYD gene expression. In the kidneys of 35 male Nellore cattle, these were divided into a control group and two treatment groups (2 x 10(6) international units of vitamin D3 administered for 2 or 8 consecutive days pre-slaughter). Vitamin D3 supplementation resulted in a significant increase in 1alpha-HYD gene expression; however, significantly increased 24-HYD gene expression was only detected in cattle that had 8 days of supplementation. The finding of upregulation of 24-HYD due to vitamin D supplementation is in line with the expected rise in 24,25-di-hydroxy-vitamin D3 synthesis observed when plasma vitamin D3 concentrations are high, stimulating excretion by the organism. On the other hand, upregulation of 1alpha-HYD was unexpected, since vitamin D3 supplementation has been reported to impact these two genes in opposite directions. We conclude that vitamin D3 metabolism in these animals is more complex than previously reported.
Assuntos
25-Hidroxivitamina D3 1-alfa-Hidroxilase/biossíntese , Bovinos/metabolismo , Colecalciferol/farmacologia , Rim/metabolismo , Esteroide Hidroxilases/biossíntese , 25-Hidroxivitamina D3 1-alfa-Hidroxilase/genética , Animais , Cálcio/sangue , Suplementos Nutricionais , Exposição Ambiental , Expressão Gênica , Gliceraldeído 3-Fosfato Desidrogenase (NADP+)/biossíntese , Masculino , Carne , Fator 1 de Elongação de Peptídeos/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Proteínas Ribossômicas/biossíntese , Esteroide Hidroxilases/genética , Luz Solar , Vitamina D3 24-HidroxilaseRESUMO
In rats, N-nitrosodiethylamine (NDEA) induces tumors mainly in the liver. This could be because various enzymes are responsible for the metabolic activation of NDEA, besides the hepatic NDEA metabolizing enzyme, CYP2E1. We examined NDEA genotoxicity and cytotoxicity in primary cultures of female rat hepatocytes; we also looked at how it affected CYP mRNA expression. Single incubation with 0.9% NaCl resulted in a mean of 0.2% apoptotic cells, which doubled with 105 µg NDEA/mL. The frequency of necrosis with NDEA treatment was also doubled. Besides the cytotoxic effects, there was also a 4-fold decrease in mitotic index and a 3-fold decrease in the percentage of cells with micronuclei. A significant increase in micronucleus cells when hepatocytes were incubated with 2.1 µg NDEA/mL suggests that DNA repair was inactive. The chromosomal aberration evaluation revealed a discrete dose-response curve. Treatment with NDEA induced increases in CYP mRNA: CYP2B2 (1.8 times) and CYP2E1 (1.6 times) with non-cytotoxic NDEA concentrations (0.21-21 µg/mL). CYP2B1 mRNA levels decreased at 0.21 µg NDEA/mL (2.5-fold), while CYP4A3 mRNA decreased 1.3-fold. NDEA treatment at 2.1 µg/ mL induced a 1.9-fold increase in CYP3A1 mRNA. Understanding the cumulative effects in target cells during precarcinogenesis is crucial to understanding the mode of action of potential carcinogens and in order to develop comprehensive chemical toxicity profiles.
Assuntos
Alquilantes/farmacologia , Hidrocarboneto de Aril Hidroxilases/biossíntese , Citocromo P-450 CYP2E1/biossíntese , Dano ao DNA/efeitos dos fármacos , Dietilnitrosamina/farmacologia , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hepatócitos/enzimologia , Esteroide Hidroxilases/biossíntese , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Feminino , Hepatócitos/patologia , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/enzimologia , Neoplasias Hepáticas/patologia , Necrose/enzimologia , Necrose/patologia , RNA Mensageiro , Ratos , Ratos Endogâmicos F344RESUMO
Primary hepatocytes are widely used in investigating drug metabolism and its toxicological effects. N-Nitrosodiethylamine (NDEA)-induced genotoxicity and cytotoxicity was used in primary cultures of female rat hepatocytes in the presence of phenobarbital (PB). PB pre-treatment (1mM) increased the number of necrotic (2-fold) and apoptotic cells (4-fold) after NDEA treatment (0.21-105 µg/mL). The mitotic indices and the number of micronucleated cells decreased, thus suggesting cytotoxicity. An increased number of chromosomal aberrations were observed after pre-treatment with PB. NDEA-treatment (0.21-21 µg/mL) induced expression of the CYP2B1 and CYP2B2 mRNA and PB treatment alone induced ~6-fold and ~2-fold increases of CYP2B1 and CYP2B2 mRNA, respectively. NDEA treatment following PB exposure increased CYP2B1 mRNA expression under all tested concentrations and also increased CYP2B2 expression at 21 and 105 µg/mL. Our data suggest that the alteration of CYP2B1/2 expression by PB increased the cytotoxicity and genotoxicity of NDEA leading to the final genotoxic metabolite.
Assuntos
Carcinógenos/toxicidade , Sistema Enzimático do Citocromo P-450/biossíntese , Dietilnitrosamina/toxicidade , Hepatócitos/efeitos dos fármacos , Mutagênicos/toxicidade , Fenobarbital/toxicidade , Regulação para Cima/efeitos dos fármacos , Animais , Hidrocarboneto de Aril Hidroxilases/biossíntese , Hidrocarboneto de Aril Hidroxilases/genética , Morte Celular/efeitos dos fármacos , Células Cultivadas , Aberrações Cromossômicas/efeitos dos fármacos , Cocarcinogênese , Citocromo P-450 CYP2B1/biossíntese , Citocromo P-450 CYP2B1/genética , Sistema Enzimático do Citocromo P-450/genética , Indução Enzimática/efeitos dos fármacos , Feminino , Hepatócitos/patologia , Micronúcleos com Defeito Cromossômico/efeitos dos fármacos , Índice Mitótico , RNA Mensageiro/metabolismo , Ratos , Esteroide Hidroxilases/biossíntese , Esteroide Hidroxilases/genéticaRESUMO
OBJECTIVE: To analyze vitamin D metabolism and response to ketoconazole, an imidazole derivative that inhibits the vitamin D-1-hydroxylase, in infants with idiopathic hypercalcemia, and hypercalciuria. STUDY DESIGN: Twenty infants (4 days-17 months) with hypercalcemia, severe hypercalciuria, and low parathyroid hormone level, (10 had nephrocalcinosis), including 10 treated with ketoconazole (3-9 mg/kg/day), were followed to the age of 2 to 51 months. Vitamin D receptor expression (VDR), 24-hydroxylase activity, and functional gene polymorphisms of vitamin D metabolism regulators VDR(rs4516035), 1-hydroxylase(rs10877012), 24-hydroxylase(rs2248359), FGF23(rs7955866), Klotho(rs9536314, rs564481, rs648202), were evaluated. RESULTS: Serum calcium levels, which occurred faster in the ketoconazole group (0.7 +/- 0.2 versus 2.4 +/- 0.6 months; P = .0076), and urinary calcium excretion (2.5 +/- 0.5 versus 4.2 +/- 1.7 months) normalized in all patients. Serum 1,25-(OH)2D levels were high normal and positively correlated to 25-(OH)D levels. Serum 24,25-(OH)2D levels were low normal, and skin fibroblasts from 1 patient showed defective up-regulation of the 24-hydroxylase by 1,25-(OH)2D despite normal VDR binding ability. An abnormally low prevalence of haplotype CC/CC for H589H/A749A in Klotho gene was found in patients and family members. CONCLUSIONS: Ketoconazole is a potentially useful and safe agent for treatment of infantile hypercalcemia. Abnormal vitamin D metabolism is suggested as the mechanism, possibly involving defective up-regulation of the 24-hydroxylase by 1,25-(OH)2D3, and the klotho-FGF23 axis.
Assuntos
Hipercalcemia/tratamento farmacológico , Hipercalcemia/etiologia , Hipercalciúria/tratamento farmacológico , Hipercalciúria/etiologia , Cetoconazol/uso terapêutico , Vitamina D/metabolismo , Cálcio/sangue , Feminino , Fator de Crescimento de Fibroblastos 23 , Haplótipos , Humanos , Lactente , Recém-Nascido , Masculino , Hormônio Paratireóideo/metabolismo , Polimorfismo Genético , Receptores de Calcitriol/biossíntese , Esteroide Hidroxilases/antagonistas & inibidores , Esteroide Hidroxilases/biossíntese , Vitamina D3 24-HidroxilaseRESUMO
While many studies have addressed the direct effects of 1alpha,25(OH)2D3 on breast cancer (BC) cells, stromal-epithelial interactions, which are important for the tumor development, have been largely ignored. In addition, high concentrations of the hormone, which cannot be attained in vivo, have been used. Our aim was to establish a more physiological breast cancer model, represented by BC tissue slices, which maintain epithelial-mesenchymal interactions, cultured with a relatively low 1alpha,25(OH)2D3 concentration, in order to evaluate the vitamin D pathway. Freshly excised human BC samples were sliced and cultured in complete culture media containing vehicle, 0.5 nM or 100 nM 1alpha,25(OH)2D3 for 24 h. BC slices remained viable for at least 24 h, as evaluated by preserved tissue morphology in hematoxylin and eosin (HE) stained sections and bromodeoxyuridine (BrdU) incorporation by 10% of tumor cells. VDR mRNA expression was detected in all samples and CYP24A1 mRNA expression was induced by 1alpha,25(OH)2D3 in both concentrations (but mainly with 100 nM). Our results indicate that the vitamin D signaling pathway is functional in BC slices, a model which preserves stromal-epithelial interactions and mimics in vivo conditions.
Assuntos
Neoplasias da Mama/metabolismo , Regulação Neoplásica da Expressão Gênica , Vitamina D/metabolismo , Idoso , Neoplasias da Mama/patologia , Bromodesoxiuridina/farmacologia , DNA Complementar/metabolismo , Relação Dose-Resposta a Droga , Feminino , Humanos , Pessoa de Meia-Idade , Modelos Biológicos , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/metabolismo , Esteroide Hidroxilases/biossíntese , Fatores de Tempo , Vitamina D3 24-HidroxilaseRESUMO
Protein restriction (PR) significantly inhibits spontaneous and chemical carcinogenesis. Several factors seem to be involved in this effect, including a decrease in body weight, cellular proliferation and DNA damage and an increase in antioxidant defenses. The current study was designed to determine modifications in some hepatic cytochromes P450 (CYPs) due to a hypoproteic diet and to investigate its implications on chemical mutagenesis. Western blot analysis showed decreases of 73, 40 and 74% in CYP1A, CYP2B and CYP2E1 protein concentrations in hepatic microsomes from animals fed a protein-restricted (6% protein) diet for 6 weeks in comparison with microsomes from rats fed a 24% protein diet during the same period. In the same way, low protein fed animals showed a 3.5-fold decrease in hepatic CYP1A1-associated ethoxyresorufin O-deethylase activity, a 6-fold decrease in CYP1A2-associated methoxyresorufin O-demethylase activity, a 1.7-fold decrease in CYP2B1-associated penthoxyresorufin O-dealkylase activity, a 9-fold decrease in CYP2B2-associated benzyloxyresorufin O-dealkylase and, finally, a 3.4-fold decrease in CYP2E1-associated 4-nitrophenol hydroxylase activity. As a result of decreased CYP hepatic protein concentrations and enzymatic activities, liver S9 from rats fed a hypoproteic diet was less efficient in activating promutagens than S9 prepared from rats fed a 24% protein diet in the Ames test. Mutagenic potency obtained with protein-restricted S9 was reduced 25-fold for 2-aminoanthracene, 1.5-fold for N-nitrosodipropylamine, 12.5-fold for N-nitrosodibutylamine, 2-fold for cyclophosphamide and N-nitrosopyrrolidine and 71-fold for N-nitrosodimethylamine. However, the mutagenic potency of benzo[a]pyrene was the same (4 revertants/ microg) with S9 derived from rats fed either a 6 or 24% protein diet.
Assuntos
Biotransformação/efeitos dos fármacos , Carcinógenos/farmacocinética , Sistema Enzimático do Citocromo P-450/biossíntese , Dieta com Restrição de Proteínas , Proteínas Alimentares/farmacologia , Microssomos Hepáticos/efeitos dos fármacos , Testes de Mutagenicidade , Mutagênicos/farmacocinética , Animais , Hidrocarboneto de Aril Hidroxilases/biossíntese , Hidrocarboneto de Aril Hidroxilases/genética , Peso Corporal/efeitos dos fármacos , Carcinógenos/toxicidade , Citocromo P-450 CYP1A1/biossíntese , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A2/biossíntese , Citocromo P-450 CYP1A2/genética , Citocromo P-450 CYP2E1/biossíntese , Citocromo P-450 CYP2E1/genética , Sistema Enzimático do Citocromo P-450/genética , Dano ao DNA , Proteínas Alimentares/administração & dosagem , Indução Enzimática/efeitos dos fármacos , Hidroliases/biossíntese , Hidroliases/genética , Masculino , Microssomos Hepáticos/enzimologia , Mutagênese , Mutagênicos/toxicidade , Oxazinas/farmacocinética , Oxazinas/toxicidade , Oxirredutases/biossíntese , Oxirredutases/genética , Ratos , Ratos Wistar , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Esteroide Hidroxilases/biossíntese , Esteroide Hidroxilases/genética , Especificidade por SubstratoRESUMO
Dichlorodiphenyltrichloroethane (DDT) is a well-known inducer of microsomal monooxygenase systems in rodent liver. However, little information is available on its effects on the sex-dependent regulation of CYPs preferentially affected. Therefore, our objective was to evaluate the effects of DDT on the sexual expression pattern of some hepatic P-450 isozymes. Single doses of technical DDT (0, 0.1, 1, 5, 10, or 100 mg/kg body wt) were administered by gavage to Wistar rats. The effects on CYPs 1A1, 2B11/2B2, 2C11, 2E1, 3A1, and 3A2, were assessed 24 h later by means of CYP protein content determined by Western blotting and/or enzyme activities participating in alkoxyresorufin and pnitrophenol metabolism. The highest dose induced 18-fold the expression of CYP3A2 in female rats without producing significant induction (< 3-fold) in males. The effects on this isozyme, which is not normally expressed in females, suggest that DDT is able to modulate sexual metabolic dimorphism, as 3A2 expression is androgen dependent. DDT did not significantly alter CYP3A1 in males, suggesting that DDT is not a pure phenobarbital (PB)-type inducer. The effects on CYP2B1/2B2 protein (19-fold) and associated enzyme activities indicated that males had a lower response threshold than females, but that the latter were able to reach a higher relative induction. The preferential induction of CYPs 2B and 3A by DDT in a sex-related manner suggest that CYP regulation could play an important role in endocrine disruption.
Assuntos
Sistema Enzimático do Citocromo P-450/biossíntese , DDT/farmacologia , Inseticidas/farmacologia , Fígado/enzimologia , Animais , Western Blotting , Citocromo P-450 CYP1A1/metabolismo , Indução Enzimática/efeitos dos fármacos , Feminino , Indicadores e Reagentes , Isoenzimas/biossíntese , Fígado/efeitos dos fármacos , Masculino , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Wistar , Caracteres Sexuais , Esteroide Hidroxilases/biossínteseRESUMO
Beta-Myrcene (MYR) is an acyclic monoterpene found in the essential oils of a variety of useful plants such as lemongrass (Cymbopogon citratus), hop, verbena, bay and others. MYR and essential oils containing this olefinic monoterpene are widely used as flavoring food additives, as fragrances in cosmetics and as scents in household products. The present study was undertaken to investigate the induction of liver monooxygenases by MYR. Female Wistar rats were treated by gavage with MYR (1000 mg/kg body weight) or corn oil (vehicle) for 1 or 3 consecutive days. Activities of ethoxycoumarin-O-deethylase (ECOD) and alkoxy-resorufin O-dealkylases (methoxy- (MROD), ethoxy- (EROD), pentoxy- (PROD) and benzyloxy-resorufin-O-dealkylation (BROD)) were determined fluorimetrically in the hepatic microsomal fraction. Exposure to MYR, either for 1 or 3 days, produced marked (13-34-fold) increases in the activities of PROD and BROD and only minor changes in ECOD, EROD and MROD. Since PROD and BROD are metabolized mainly by CYP2B isoenzymes, these results suggest that MYR induces this phenobarbital-inducible P450 subfamily. The induction of CYP2B isoenzymes was confirmed by SDS-PAGE and immunoblotting. Levels of apoproteins CYP2B1/2B2 were increased 8.2-fold after treatment with MYR (1000 mg/kg body wt, 3 days). Results from this study therefore indicate that MYR is an inducer of isoenzymes belonging to CYP2B subfamily.