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1.
Med J Malaysia ; 75(2): 169-170, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32281601

RESUMO

Acute ischemic stroke (AIS) and acute ST-elevation myocardial infarction (STEMI) are leading causes of mortality worldwide. Concurrent AIS presentation with STEMI is rare and potentially fatal. Most importantly to date many centres in Malaysia are still not aware on how to treat this condition. We report a case of AIS, which was treated with intravenous tenecteplase (TNK) according to ischemic stroke dosage and lead to improvement of neurological deficit.


Assuntos
Contraindicações , Fibrinolíticos/administração & dosagem , Infarto do Miocárdio com Supradesnível do Segmento ST/tratamento farmacológico , Acidente Vascular Cerebral/tratamento farmacológico , Tenecteplase/administração & dosagem , Administração Intravenosa , Adulto , Humanos , Malásia , Masculino
2.
Med J Malaysia ; 71(5): 288-291, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-28064297

RESUMO

Interventional Pain Procedures (IPPs) is a relatively new treatment modality for chronic pain in Malaysia. The Interventional Pain Service (IPS) newly set up in our institution is led by a pain neurosurgeon and provides a whole package of multimodal pain management including different range of IPPs. This clinical audit is to examine the quality of IPPs performed within the IPS in our institution since its initiation. A total of 87 IPPs were performed on 56 chronic pain patients over 3-year duration. As high as 81.8% of the procedures were effective and 81.5% of patients were satisfied. Only one minor transient complication occurred after an intradiscal procedure but none resulted in death or permanent disability. Thus, safe and effective IPPs can be provided as part of IPS in a local neurosurgical pain centre to bring more comprehensive and less fragmented care for chronic pain patients.


Assuntos
Auditoria Clínica , Manejo da Dor , Humanos , Malásia , Dor , Satisfação do Paciente
3.
Toxicol Appl Pharmacol ; 282(1): 77-89, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25478736

RESUMO

The intracellular level of bilirubin (BR), an endogenous antioxidant that is cytotoxic at high concentrations, is tightly controlled within the optimal therapeutic range. We have recently described a concerted intracellular BR regulation by two microsomal enzymes: heme oxygenase 1 (HMOX1), essential for BR production and cytochrome P450 2A5 (CYP2A5), a BR oxidase. Herein, we describe targeting of these enzymes to hepatic mitochondria during oxidative stress. The kinetics of microsomal and mitochondrial BR oxidation were compared. Treatment of DBA/2J mice with 200mgpyrazole/kg/day for 3days increased hepatic intracellular protein carbonyl content and induced nucleo-translocation of Nrf2. HMOX1 and CYP2A5 proteins and activities were elevated in microsomes and mitoplasts but not the UGT1A1, a catalyst of BR glucuronidation. A CYP2A5 antibody inhibited 75% of microsomal BR oxidation. The inhibition was absent in control mitoplasts but elevated to 50% after treatment. An adrenodoxin reductase antibody did not inhibit microsomal BR oxidation but inhibited 50% of mitochondrial BR oxidation. Ascorbic acid inhibited 5% and 22% of the reaction in control and treated microsomes, respectively. In control mitoplasts the inhibition was 100%, which was reduced to 50% after treatment. Bilirubin affinity to mitochondrial and microsomal CYP2A5 enzyme is equally high. Lastly, the treatment neither released cytochrome c into cytoplasm nor dissipated membrane potential, indicating the absence of mitochondrial membrane damage. Collectively, the observations suggest that BR regulatory enzymes are recruited to mitochondria during oxidative stress and BR oxidation by mitochondrial CYP2A5 is supported by mitochondrial mono-oxygenase system. The induced recruitment potentially confers membrane protection.


Assuntos
Hidrocarboneto de Aril Hidroxilases/metabolismo , Bilirrubina/metabolismo , Heme Oxigenase-1/metabolismo , Fígado/enzimologia , Proteínas de Membrana/metabolismo , Mitocôndrias Hepáticas/enzimologia , Estresse Oxidativo , Transporte Ativo do Núcleo Celular , Adaptação Fisiológica , Animais , Antioxidantes/farmacologia , Hidrocarboneto de Aril Hidroxilases/antagonistas & inibidores , Família 2 do Citocromo P450 , Inibidores Enzimáticos/farmacologia , Ferredoxina-NADP Redutase/metabolismo , Glucuronosiltransferase/metabolismo , Cinética , Fígado/efeitos dos fármacos , Masculino , Camundongos Endogâmicos DBA , Microssomos Hepáticos/enzimologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/metabolismo , Oxidantes/farmacologia , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Carbonilação Proteica
4.
Toxicol Appl Pharmacol ; 289(1): 30-9, 2015 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-26343999

RESUMO

Human cytochrome P450 (CYP) 2A6 enzyme has been proposed to play a role in cellular defence against chemical-induced oxidative stress. The encoding gene is regulated by various stress activated transcription factors. This paper demonstrates that p53 is a novel transcriptional regulator of the gene. Sequence analysis of the CYP2A6 promoter revealed six putative p53 binding sites in a 3kb proximate promoter region. The site closest to transcription start site (TSS) is highly homologous with the p53 consensus sequence. Transfection with various stepwise deletions of CYP2A6-5'-Luc constructs--down to -160bp from the TSS--showed p53 responsiveness in p53 overexpressed C3A cells. However, a further deletion from -160 to -74bp, including the putative p53 binding site, totally abolished the p53 responsiveness. Electrophoretic mobility shift assay with a probe containing the putative binding site showed specific binding of p53. A point mutation at the binding site abolished both the binding and responsiveness of the recombinant gene to p53. Up-regulation of the endogenous p53 with benzo[α]pyrene--a well-known p53 activator--increased the expression of the p53 responsive positive control and the CYP2A6-5'-Luc construct containing the intact p53 binding site but not the mutated CYP2A6-5'-Luc construct. Finally, inducibility of the native CYP2A6 gene by benzo[α]pyrene was demonstrated by dose-dependent increases in CYP2A6 mRNA and protein levels along with increased p53 levels in the nucleus. Collectively, the results indicate that p53 protein is a regulator of the CYP2A6 gene in C3A cells and further support the putative cytoprotective role of CYP2A6.


Assuntos
Citocromo P-450 CYP2A6/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Sequência de Bases , Sítios de Ligação , Linhagem Celular Tumoral , Citocromo P-450 CYP2A6/genética , Dano ao DNA , Ensaio de Desvio de Mobilidade Eletroforética , Fator 4 Nuclear de Hepatócito/genética , Fator 4 Nuclear de Hepatócito/metabolismo , Humanos , Células MCF-7 , Dados de Sequência Molecular , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/genética , Regiões Promotoras Genéticas , Ligação Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteína Supressora de Tumor p53/genética , Regulação para Cima
5.
Int J Dent Hyg ; 13(3): 199-205, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25040653

RESUMO

OBJECTIVE: To assess Malaysian dental therapists' perceptions of their job satisfaction and future roles. METHODS: A nationwide postal survey involving all Malaysian dental therapists who met the inclusion criteria (n = 1726). RESULTS: The response rate was 76.8%. All respondents were females; mean age 35.4 years (SD = 8.4). Majority were married (85.5%) and more than one-half had a working experience of <10 years (56.1%). Majority worked in community dental service (94.3%) and in urban areas (61.7%). Overall, they were highly satisfied with most aspects of their career. However, they were least satisfied with administrative workload (58.1%), career advancement opportunities (51.9%) and remuneration package; specifically income (45.2%), allowances (45.2%) and non-commensurate between pay and performance (44.0%). Majority perceived their role as very important in routine clinical tasks such as examination and diagnosis, preventive treatment, extraction of deciduous teeth and oral health promotion. However, fewer than one-half consider complex treatment such as placement of preformed crowns on deciduous teeth (37.1%) and extraction of permanent teeth (37.2%) as very important tasks. CONCLUSION: Majority expressed high career satisfaction with most aspects of their employment but expressed low satisfaction in remuneration, lack of career advancement opportunities and administrative tasks. We conclude that most Malaysian dental therapists have positive perceptions of their current roles but do not favour wider expansion of their roles. These findings imply that there was a need to develop a more attractive career pathway for therapists to ensure sustainability of effective primary oral healthcare delivery system for Malaysia's children.


Assuntos
Atitude do Pessoal de Saúde , Auxiliares de Odontologia/psicologia , Satisfação no Emprego , Adulto , Mobilidade Ocupacional , Serviços de Saúde Comunitária , Estudos Transversais , Delegação Vertical de Responsabilidades Profissionais , Auxiliares de Odontologia/tendências , Assistência Odontológica , Feminino , Promoção da Saúde , Humanos , Renda , Relações Interprofissionais , Malásia , Estado Civil , Pessoa de Meia-Idade , Saúde Bucal , Atenção Primária à Saúde , Relações Profissional-Paciente , Salários e Benefícios , Serviços Urbanos de Saúde , Carga de Trabalho , Local de Trabalho
6.
Genes Environ ; 46(1): 15, 2024 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-38982523

RESUMO

BACKGROUND: Exposure to chemical mixtures inherent in air pollution, has been shown to be associated with the risk of breast and lung cancers. However, studies on the molecular mechanisms of exposure to a mixture of these pollutants, such as hydrocarbons, in the development of breast and lung cancers are scarce. We utilized in silico toxicogenomic analysis to elucidate the molecular pathways linked to both cancers that are influenced by exposure to a mixture of selected hydrocarbons. The Comparative Toxicogenomics Database and Cytoscape software were used for data mining and visualization. RESULTS: Twenty-five hydrocarbons, common in air pollution with carcinogenicity classification of 1 A/B or 2 (known/presumed or suspected human carcinogen), were divided into three groups: alkanes and alkenes, halogenated hydrocarbons, and polyaromatic hydrocarbons. The in silico data-mining revealed 87 and 44 genes commonly interacted with most of the investigated hydrocarbons are linked to breast and lung cancer, respectively. The dominant interactions among the common genes are co-expression, physical interaction, genetic interaction, co-localization, and interaction in shared protein domains. Among these genes, only 16 are common in the development of both cancers. Benzo(a)pyrene and tetrachlorodibenzodioxin interacted with all 16 genes. The molecular pathways potentially affected by the investigated hydrocarbons include aryl hydrocarbon receptor, chemical carcinogenesis, ferroptosis, fluid shear stress and atherosclerosis, interleukin 17 signaling pathway, lipid and atherosclerosis, NRF2 pathway, and oxidative stress response. CONCLUSIONS: Within the inherent limitations of in silico toxicogenomics tools, we elucidated the molecular pathways associated with breast and lung cancer development potentially affected by hydrocarbons mixture. Our findings indicate adaptive responses to oxidative stress and inflammatory damages are instrumental in the development of both cancers. Additionally, ferroptosis-a non-apoptotic programmed cell death driven by lipid peroxidation and iron homeostasis-was identified as a new player in these responses. Finally, AHR potential involvement in modulating IL-8, a critical gene that mediates breast cancer invasion and metastasis to the lungs, was also highlighted. A deeper understanding of the interplay between genes associated with these pathways, and other survival signaling pathways identified in this study, will provide invaluable knowledge in assessing the risk of inhalation exposure to hydrocarbons mixture. The findings offer insights into future in vivo and in vitro laboratory investigations that focus on inhalation exposure to the hydrocarbons mixture.

7.
Anticancer Drugs ; 24(8): 852-61, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23764760

RESUMO

There is growing interest in the discovery of bioactive metabolites from endophytes as an alternative source of therapeutics. Identification of their therapeutic targets is essential in understanding the underlying mechanisms and enhancing the resultant therapeutic effects. As such, bioactive compounds produced by endophytic fungi from plants at the National Park, Pahang, Malaysia, were investigated. Five known compounds were identified using LC-UV-MS-NMR and they include trichodermol, 7-epi-brefeldin A, (3R,4S)-4-hydroxymellein, desmethyl-lasiodiplodin and cytochalasin D. The present study went on to investigate the potential anticancer effects of these compounds and the corresponding molecular mechanisms of the lead compound against human breast adenocarcinoma, MCF-7. For the preliminary screening, the cytotoxicity and apoptotic effects of these compounds against MCF-7 were examined. The compounds were also tested against noncarcinogenic hepatocytes (WRL68). The differential cytotoxicity was then determined using the MTT assay. Desmethyl-lasiodiplodin was found to suppress the growth of MCF-7, yielding an inhibitory concentration (IC50) that was seven-fold lower than that of the normal cells. The cytotoxic effect of desmethyl-lasiodiplodin was accompanied by apoptosis. Subsequent analysis demonstrated increased expression levels of caspase 3, c-myc and p53. Further, desmethyl-lasiodiplodin resulted in inhibition of monocyte chemotactic protein (MCP)-3, a cytokine involved in cell survival and metastasis. Hence, this study proposed that desmethyl-lasiodiplodin inhibited growth and survival of MCF-7 through the induction of apoptosis. This anticancer effect is mediated, in part, by upregulation of apoptotic genes and downregulation of MCP-3. As desmethyl-lasiodiplodin elicited minimal impact against normal hepatocytes, our findings also imply its potential use as a specific apoptotic agent in breast cancer treatment.


Assuntos
Antineoplásicos/farmacologia , Proteínas Reguladoras de Apoptose/metabolismo , Apoptose/efeitos dos fármacos , Neoplasias da Mama/patologia , Quimiocina CCL7/metabolismo , Micotoxinas/farmacologia , Zearalenona/análogos & derivados , Animais , Antineoplásicos/isolamento & purificação , Antineoplásicos/toxicidade , Apoptose/genética , Proteínas Reguladoras de Apoptose/genética , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Caspase 3/genética , Caspase 3/metabolismo , Proliferação de Células/efeitos dos fármacos , Quimiocina CCL7/genética , Cromatografia Líquida , Relação Dose-Resposta a Droga , Regulação para Baixo , Endófitos/química , Feminino , Humanos , Concentração Inibidora 50 , Células MCF-7 , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Camundongos , Micotoxinas/isolamento & purificação , Micotoxinas/toxicidade , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Espectrofotometria Ultravioleta , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Regulação para Cima , Zearalenona/isolamento & purificação , Zearalenona/farmacologia , Zearalenona/toxicidade
8.
Toxicol Appl Pharmacol ; 261(1): 50-8, 2012 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-22465937

RESUMO

The mouse cytochrome P450 (CYP) 2A5 has recently been shown to function as hepatic "Bilirubin Oxidase" (Abu-Bakar, A., et al., 2011. Toxicol. Appl. Pharmacol. 257, 14-22). To date, no information is available on human CYP isoforms involvement in bilirubin metabolism. In this paper we provide novel evidence for human CYP2A6 metabolising the tetrapyrrole bilirubin. Incubation of bilirubin with recombinant yeast microsomes expressing the CYP2A6 showed that bilirubin inhibited CYP2A6-dependent coumarin 7-hydroxylase activity to almost 100% with an estimated K(i) of 2.23 µM. Metabolite screening by a high-performance liquid chromatography/electrospray ionisation mass spectrometry indicated that CYP2A6 oxidised bilirubin to biliverdin and to three other smaller products with m/z values of 301, 315 and 333. Molecular docking analyses indicated that bilirubin and its positively charged intermediate interacted with key amino acid residues at the enzyme's active site. They were stabilised at the site in a conformation favouring biliverdin formation. By contrast, the end product, biliverdin was less fitting to the active site with the critical central methylene bridge distanced from the CYP2A6 haem iron facilitating its release. Furthermore, bilirubin treatment of HepG2 cells increased the CYP2A6 protein and activity levels with no effect on the corresponding mRNA. Co-treatment with cycloheximide (CHX), a protein synthesis inhibitor, resulted in increased half-life of the CYP2A6 compared to cells treated only with CHX. Collectively, the observations indicate that the CYP2A6 may function as human "Bilirubin Oxidase" where bilirubin is potentially a substrate and a regulator of the enzyme.


Assuntos
Hidrocarboneto de Aril Hidroxilases/metabolismo , Bilirrubina/metabolismo , Biliverdina/metabolismo , Microssomos/metabolismo , Cromatografia Líquida de Alta Pressão , Cicloeximida/farmacologia , Citocromo P-450 CYP2A6 , Meia-Vida , Células Hep G2 , Humanos , Microssomos/enzimologia , Modelos Moleculares , RNA Mensageiro/metabolismo , Saccharomyces cerevisiae/enzimologia , Espectrometria de Massas por Ionização por Electrospray
9.
Curr Drug Metab ; 23(5): 355-373, 2022 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-35345986

RESUMO

Cancer is a leading cause of mortality globally. Cytochrome P450 (CYP) enzymes play a pivotal role in the biotransformation of both endogenous and exogenous compounds. Various lines of evidence from epidemiological, animal, and clinical studies point to the instrumental role of CYPs in cancer initiation, metastasis, and prevention. Substantial research has found that CYPs are involved in activating different carcinogenic chemicals in the environment, such as polycyclic aromatic hydrocarbons and tobacco-related nitrosamines. Electrophilic intermediates produced from these chemicals can covalently bind to DNA, inducing mutation and cellular transformation that collectively result in cancer development. While bioactivation of procarcinogens and promutagens by CYPs has long been established, the role of CYP-derived endobiotics in carcinogenesis has only emerged in recent years. Eicosanoids derived from arachidonic acid via CYP oxidative pathways have been implicated in tumorigenesis, cancer progression and metastasis. The purpose of this review is to update the current state of knowledge about the molecular cancer mechanism involving CYPs with a focus on the biochemical and biotransformation mechanisms in the various CYP-mediated carcinogenesis and the role of CYP-derived reactive metabolites, from both external and endogenous sources, in cancer growth and tumor formation.


Assuntos
Sistema Enzimático do Citocromo P-450 , Neoplasias , Animais , Biotransformação , Carcinogênese , Sistema Enzimático do Citocromo P-450/metabolismo , Neoplasias/patologia , Oxirredução
10.
Toxicol Appl Pharmacol ; 257(1): 14-22, 2011 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-21871474

RESUMO

We have previously shown that bilirubin (BR), a breakdown product of haem, is a strong inhibitor and a high affinity substrate of the mouse cytochrome P450 2A5 (CYP2A5). The antioxidant BR, which is cytotoxic at high concentrations, is potentially useful in cellular protection against oxygen radicals if its intracellular levels can be strictly controlled. The mechanisms that regulate cellular BR levels are still obscure. In this paper we provide preliminary evidence for a novel function of CYP2A5 as hepatic "BR oxidase". A high-performance liquid chromatography/electrospray ionisation mass spectrometry screening showed that recombinant yeast microsomes expressing the CYP2A5 oxidise BR to biliverdin, as the main metabolite, and to three other smaller products with m/z values of 301, 315 and 333. The metabolic profile is significantly different from that of chemical oxidation of BR. In chemical oxidation the smaller products were the main metabolites. This suggests that the enzymatic reaction is selective, towards biliverdin production. Bilirubin treatment of primary hepatocytes increased the CYP2A5 protein and activity levels with no effect on the corresponding mRNA. Co-treatment with cycloheximide (CHX), a protein synthesis inhibitor, resulted in increased half-life of the CYP2A5 compared to cells treated only with CHX. Collectively, the observations suggest that the CYP2A5 is potentially an inducible "BR oxidase" where BR may accelerate its own metabolism through stabilization of the CYP2A5 protein. It is possible that this metabolic pathway is potentially part of the machinery controlling intracellular BR levels in transient oxidative stress situations, in which high amounts of BR are produced.


Assuntos
Hidrocarboneto de Aril Hidroxilases/fisiologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/fisiologia , Animais , Hidrocarboneto de Aril Hidroxilases/biossíntese , Hidrocarboneto de Aril Hidroxilases/metabolismo , Bilirrubina/metabolismo , Bilirrubina/fisiologia , Biliverdina/biossíntese , Cicloeximida/farmacologia , Citocromo P-450 CYP2A6 , Família 2 do Citocromo P450 , Indução Enzimática , Hepatócitos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos DBA , Microssomos/metabolismo , Oxirredução , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/biossíntese , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Saccharomyces cerevisiae/metabolismo
11.
Basic Clin Pharmacol Toxicol ; 123 Suppl 5: 72-80, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29788535

RESUMO

The murine cytochrome P450 2a5 (Cyp2a5) gene is regulated by complex interactions of various stress-activated transcription factors (TFs). Elevated Cyp2a5 transcription under chemical-induced stress conditions is achieved by interplay between the various TFs - including as aryl hydrocarbon receptor (AhR) and nuclear factor (erythroid-derived 2)-like 2 wild-type (Nrf2) - at the 'stress-responding' cluster of response elements on the Cyp2a5 promoter, as well as through mRNA stabilization mediated by interaction of the stress-activated heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) with the 3'-UTR of the CYP2A5 mRNA. We designed a unique toxicity pathway-based reporter assay to include regulatory regions from both the 5' and the 3' untranslated regions of Cyp2a5 in a luciferase reporter plasmid to reflect in vivo responses to chemical insult. Human breast cancer MCF-7 cells were stably transfected with pGL4.38-Cyp2a5_Wt3k (wild-type) or mutant - pGL4.38-Cyp2a5_StREMut and pGL4.38-Cyp2a5_XREMut - reporter gene to monitor chemical-induced cellular response mediated by AhR and Nrf2 signalling. The recombinant cells were treated with representative of AhR agonist, polycyclic aromatic hydrocarbons, brominated flame retardant, fluorosurfactant, aromatic organic compound and metal, to determine the sensitivity of the Cyp2a5 promoter-based gene reporter assays to chemical insults by measuring the LC50 and EC50 of the respective chemicals. The three assays are sensitive to sublethal cellular responses of chemicals, which is an ideal feature for toxicity pathway-based bioassay for toxicity prediction. The wild-type reporter responded well to chemicals that activate crosstalk between the AhR and Nrf2, whilst the mutant reporters effectively gauge cellular response driven by either Nrf2/StRE or AhR/XRE signalling. Thus, the three gene reporter assays could be used tandemly to determine the predominant toxicity pathway of a given compound.


Assuntos
Hidrocarboneto de Aril Hidroxilases/genética , Bioensaio/métodos , Família 2 do Citocromo P450/genética , Genes Reporter/genética , Regiões Promotoras Genéticas/genética , Regiões 3' não Traduzidas/genética , Células A549 , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Humanos , Luciferases/genética , Células MCF-7 , Mutagênese Sítio-Dirigida , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Testes de Toxicidade/métodos
12.
Biochem Pharmacol ; 70(10): 1527-35, 2005 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-16183037

RESUMO

Oxidative metabolism of bilirubin (BR) -- a breakdown product of haem with cytoprotective and toxic properties -- is an important route of detoxification in addition to glucuronidation. The major enzyme(s) involved in this oxidative degradation are not known. In this paper, we present evidence for a major role of the hepatic cytochrome P450 2A5 (Cyp2a5) in BR degradation during cadmium intoxication, where the BR levels are elevated following induction of haem oxygenase-1 (HO-1). Treatment of DBA/2J mice with CdCl(2) induced both the Cyp2a5 and HO-1, and increased the microsomal BR degradation activity. By contrast, the total cytochrome P450 (CYP) content and the expression of Cyp1a2 were down-regulated by the treatment. The induction of the HO-1 and Cyp2a5 was substantial at the mRNA, protein and enzyme activity levels. In each case, the up-regulation of HO-1 preceded that of Cyp2a5 with a 5-10h interval. BR totally inhibited the microsomal Cyp2a5-dependent coumarin hydroxylase activity, with an IC(50) approximately equal to the substrate concentration. The 7-methoxyresorufin 7-O-demethylase (MROD) activity, catalyzed mainly by the Cyp1a2, was inhibited up to 36% by BR. The microsomal BR degradation was inhibited by coumarin and a monoclonal antibody against the Cyp2a5 by about 90%. Furthermore, 7-methoxyresorufin, a substrate for the Cyp1a2, inhibited BR degradation activity by approximately 20%. In sum, the results strongly suggest a major role for Cyp2a5 in the oxidative degradation of BR. Secondly, the coordinated up-regulation of the HO-1 and Cyp2a5 during Cd-mediated injury implicates a network of enzyme systems in the maintenance of balancing BR production and elimination.


Assuntos
Hidrocarboneto de Aril Hidroxilases/farmacologia , Bilirrubina/metabolismo , Microssomos Hepáticos/metabolismo , Oxigenases de Função Mista/farmacologia , Animais , Hidrocarboneto de Aril Hidroxilases/antagonistas & inibidores , Hidrocarboneto de Aril Hidroxilases/genética , Hidrocarboneto de Aril Hidroxilases/metabolismo , Bilirrubina/química , Cloreto de Cádmio/administração & dosagem , Cloreto de Cádmio/efeitos adversos , Cloreto de Cádmio/metabolismo , Citocromo P-450 CYP2A6 , Inibidores das Enzimas do Citocromo P-450 , Sistema Enzimático do Citocromo P-450/metabolismo , Família 2 do Citocromo P450 , Heme Oxigenase-1/biossíntese , Heme Oxigenase-1/genética , Heme Oxigenase-1/metabolismo , Inativação Metabólica/genética , Inativação Metabólica/fisiologia , Injeções Intraperitoneais , Fígado/química , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos DBA , Microssomos Hepáticos/química , Microssomos Hepáticos/efeitos dos fármacos , Oxigenases de Função Mista/antagonistas & inibidores , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Oxazinas/antagonistas & inibidores , Oxazinas/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Oxirredutases/antagonistas & inibidores , Oxirredutases/metabolismo , RNA Mensageiro , Fatores de Tempo , Regulação para Cima/efeitos dos fármacos
13.
Fundam Clin Pharmacol ; 29(2): 131-49, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25659970

RESUMO

Zinc is the authoritative metal which is present in our body, and reactive zinc metal is crucial for neuronal signaling and is largely distributed within presynaptic vesicles. Zinc also plays an important role in synaptic function. At cellular level, zinc is a modulator of synaptic activity and neuronal plasticity in both development and adulthood. Different importers and transporters are involved in zinc homeostasis. ZnT-3 is a main transporter involved in zinc homeostasis in the brain. It has been found that alterations in brain zinc status have been implicated in a wide range of neurological disorders including impaired brain development and many neurodegenerative disorders such as Alzheimer's disease, and mood disorders including depression, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and prion disease. Furthermore, zinc has also been implicated in neuronal damage associated with traumatic brain injury, stroke, and seizure. Understanding the mechanisms that control brain zinc homeostasis is thus critical to the development of preventive and treatment strategies for these and other neurological disorders.


Assuntos
Encefalopatias/metabolismo , Encéfalo/metabolismo , Zinco/metabolismo , Animais , Transporte Biológico/fisiologia , Encéfalo/patologia , Encefalopatias/diagnóstico , Lesões Encefálicas/diagnóstico , Lesões Encefálicas/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Homeostase/fisiologia , Humanos , Doenças Neurodegenerativas/diagnóstico , Doenças Neurodegenerativas/metabolismo , Acidente Vascular Cerebral/diagnóstico , Acidente Vascular Cerebral/metabolismo
14.
Toxicol Lett ; 148(3): 199-210, 2004 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-15041070

RESUMO

Modulation of the cytochrome P450 (CYP) monooxygenase system by cadmium was investigated in male, adult DBA/2J mice treated with a single dose (16 micromol/kg body weight, i.p.) of cadmium chloride (CdCl2). Total CYP content of liver and kidney microsomes decreased maximally (56% and 85%, respectively) 24 and 18 h, respectively, after CdCl2 treatment. Progressive increases of hepatic coumarin 7-hydroxylase (COH) activity; indicative of CYP2A5 activity, relative to the total CYP content were seen at 8 h (2-fold), 12 h (3-fold), 18 h (12-fold), and 24 h (15-fold). Similar changes were seen in the kidney. Liver and kidney CYP2A5 mRNA levels increased maximally 12 and 4 h after treatment and decreased to almost half 6 h later. In contrast, kidney and liver CYP2A5 protein levels increased maximally at 18 and 24 h. The CYP2A5 mRNA levels in the kidney and liver increased after Cd treatment in Nrf2 +/+ but not in Nrf2 -/- mouse. This study demonstrates that hepatic and kidney CYP2A5 is upregulated by cadmium with a somewhat faster response in the kidney than the liver. The strong upregulation of the CYP2A5 both at mRNA and enzyme activity levels, with a simultaneous decrease in the total CYP concentration suggest an unusual mode of regulation of CYP2A5 in response to cadmium exposure, amongst the CYP enzymes. The observed decrease in the mRNA but not in protein levels after maximal induction may suggest involvement of post-transcriptional mechanisms in the regulation. Upregulation of CYP2A5 by cadmium in the Nrf2 +/+ mice but not in the Nrf2-/- mice indicates a role for this transcription factor in the regulation.


Assuntos
Hidrocarboneto de Aril Hidroxilases/biossíntese , Intoxicação por Cádmio/metabolismo , Proteínas de Ligação a DNA/fisiologia , Rim/enzimologia , Fígado/enzimologia , Oxigenases de Função Mista/biossíntese , RNA Mensageiro/biossíntese , Transativadores/fisiologia , Doença Aguda , Animais , Hidrocarboneto de Aril Hidroxilases/metabolismo , Northern Blotting , Western Blotting , Intoxicação por Cádmio/enzimologia , Citocromo P-450 CYP2A6 , Família 2 do Citocromo P450 , Relação Dose-Resposta a Droga , Rim/efeitos dos fármacos , Fígado/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos DBA , Camundongos Knockout , Microssomos/enzimologia , Microssomos/metabolismo , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/metabolismo , Oxigenases de Função Mista/metabolismo , Fator 2 Relacionado a NF-E2 , Reação em Cadeia da Polimerase Via Transcriptase Reversa
15.
Meat Sci ; 25(3): 187-97, 1989.
Artigo em Inglês | MEDLINE | ID: mdl-22054512

RESUMO

Singular and combined effects of added water, sodium erythorbate and storage time on salt soluble protein extractability, bacteriological and chemical characteristics of preblended hot-boned beef were evaluated. Waterholding and gel forming capacities of preblended hot-boned beef containing either 0, 10 or 20% added water were determined. Significant interactions between added water level and storage time on microbial counts and between sodium erythorbate level and storage time on thiobarbituric acid values and residual nitrite levels were noted. The presence of sodium erythorbate resulted in a more (P < 0·05) rapid rate of nitrite disappearance, but it did not affect (P > 0·05) microbial counts. Salt-soluble protein extractability was not affected (P > 0·05) by added water, but more protein could be extracted with increasing storage time. A trend existed to suggest that the presence of added water in the meat preblends slightly improved the gel formation and waterholding capacities.

16.
Med J Malaysia ; 59 Suppl B: 135-6, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15468855

RESUMO

Poly (p-phenylene vinylene) (PPV) was synthesized from p-xylylene bis(tetrahydrothiophenium chloride) using the Wessling route and characterized by Fourier Transform Infra-Red (FTIR) and UV-visible (UV-VIS) spectroscopic techniques. The significance of thermal treatment along with evolution of precursor polymer to polymer PPV was also studied through these spectroscopic techniques. Thermally Stimulated Current (TSC) measurements indicated the presence of crystallization, sulphonium group which occurred through the evolution from precursor polymer to polymer PPV during thermal treatment.


Assuntos
Polímeros/síntese química , Polivinil/síntese química , Humanos , Polímeros/análise , Polivinil/análise , Espectroscopia de Infravermelho com Transformada de Fourier
17.
Curr Drug Metab ; 14(1): 137-50, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22497566

RESUMO

The mouse hepatic cytochrome P450 (CYP) 2A5 and its human orthologue CYP2A6 catalyse the metabolism of a number of drugs and toxins, such as halothane and aflatoxin B1. The enzymes are named "Coumarin 7-hydroxylase" and "Nicotine Hydroxylase", respectively, by virtue of their high affinity and specific activity towards these compounds. Bilirubin, the breakdown product of haem, has been suggested to be the endogenous substrate for both enzymes. Uniquely, CYP2A5 and CYP2A6 are induced during pathological conditions associated with liver injury when the function of most other CYP enzymes is compromised, which suggests an exceptional mode of regulation of the corresponding genes. Regulation of these genes is indeed complex where the promoters interact with multiple stress-activated transcription factors. The Cyp2a5 promoter contains a "stress-responding" cluster of binding motifs, which interact with major mediators of toxic insults including nuclear factor-E2 p45-related factor 2 (Nrf2) and aryl hydrocarbon receptor (AhR). These interactions are crucial in the up-regulation of the genes under stress conditions. Additionally, elevated transcription is also achieved through mRNA stabilisation mediated by interaction of the stress activated heterogenous ribonucleoprotein A1 (hnRNP A1) with the 3'UTR of the CYP2A5/CYP2A6 mRNA. The up-regulation via enhanced transcription combined with mRNA stabilisation, as seen in some of the stress situations, leads to a particularly strong, fast and persistent response. This review brings together knowledge obtained from studies in our laboratories and others' on regulation of Cyp2a5/CYP2A6 genes in response to toxic insults and toxicological significance of their catalytic activities that may provide clues to a functional role of the enzymes in relation to liver toxicity.


Assuntos
Hidrocarboneto de Aril Hidroxilases/genética , Hepatopatias/patologia , Fígado/patologia , Animais , Hidrocarboneto de Aril Hidroxilases/metabolismo , Bilirrubina/metabolismo , Citocromo P-450 CYP2A6 , Família 2 do Citocromo P450 , Regulação da Expressão Gênica , Humanos , Hepatopatias/genética , Camundongos , Preparações Farmacêuticas/metabolismo , Regiões Promotoras Genéticas , RNA Mensageiro/metabolismo , Fatores de Transcrição/metabolismo , Regulação para Cima
18.
J Arthropod Borne Dis ; 6(1): 28-35, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23293776

RESUMO

BACKGROUND: Melaleuca cajuputi essential oil in aerosol spray was evaluated against the dengue vectors Aedes aegypti and Ae. albopictus at low cost housing flats in Section 10, Setapak, Kuala Lumpur, Malaysia. METHODS: ESSENTIAL OIL IN AEROSOL VIZ: 5% and 10% of concentrations were sprayed for 5 seconds each towards hung mosquitoes in 5 cylindrical net cages. Aerosol weights were recorded before and after spraying to determine discharge rates. Knockdown and mortality number were observed and compared to MS standard aerosol which contain 0.07% prallethrin and 0.05% d-phenothrin as positive control and aerosol contain 40% kerosene and 60% LPG was used as negative control. RESULTS: High knockdown and mortality was observed in both species of mosquitoes towards MS standard aerosol. There was a significant difference (P< 0.05) of mortality and knockdown between 5% and 10% of essential oil aerosol and 5% and 10% essential oil between MS standard. For 5% essential oil, mean percentage (%) of knockdown and mortality of Ae. aegypti displayed slightly higher compared to Ae. albopictus. Spraying with 5% M. cajuputi essential oil aerosol indicated a knockdown of Ae. aegypti 5.60±1.18 and mortality of 22.90±4.22 while Ae. albopictus showed 4.60±0.89 knockdown and 20.00±2.85 mortality. The 10% essential oil concentration gave 23.60±1.68 knockdown and 48.05±0.37 mortality for Ae. aegypti. Ae. albopictus gave 23.00±3.16 knockdown and 44.20 ± 2.10 mortality respectively. CONCLUSIONS: Extracts of essential oils does possessed an adulticidal effects and could be considered and utilized for future dengue vectors control.

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