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1.
J Toxicol Environ Health A ; 78(23-24): 1385-408, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26594896

RESUMO

Anecdotal reports in the press and epidemiological studies suggest that deployment to Iraq and Afghanistan may be associated with respiratory diseases and symptoms in U.S. military personnel and veterans. Exposures during military operations were complex, but virtually all service members were exposed to high levels of respirable, geogenic dust. Inhalation of other dusts has been shown to be associated with adverse health effects, but the pulmonary toxicity of ambient dust from Iraq has not been previously studied. The relative toxicity of Camp Victory dust was evaluated by comparing it to particulate matter from northern Kuwait, a standard U.S. urban dust, and crystalline silica using a single intratracheal instillation in rats. Lung histology, protein levels, and cell counts were evaluated in the bronchoalveolar lavage fluid 1-150 d later. The Iraq dust provoked an early significant, acute inflammatory response. However, the level of inflammation in response to the Iraq dust, U.S. urban dust, and Kuwait dust rapidly declined and was nearly at control levels by the end of the study At later times, animals exposed to the Iraq, U.S. urban, or Kuwait dusts showed increased small airway remodeling and emphysema compared to silica-exposed and control animals without evidence of fibrosis or premalignant changes. The severity and persistence of pulmonary toxicity of these three dusts from the Middle East resemble those of a U.S. urban dust and are less than those of silica. Therefore, Iraq dust exposure is not highly toxic, but similar to other poorly soluble low-toxicity dusts.


Assuntos
Poluentes Atmosféricos/toxicidade , Líquido da Lavagem Broncoalveolar/química , Exposição por Inalação , Pulmão/efeitos dos fármacos , Material Particulado/toxicidade , Animais , Poeira/análise , Iraque , Pulmão/patologia , Masculino , Ratos , Ratos Sprague-Dawley , Estações do Ano , Fatores de Tempo
2.
Toxicology ; 257(3): 161-71, 2009 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-19150385

RESUMO

Single-walled carbon nanotubes (SWCNT) represent a novel material with unique electronic and mechanical properties. The extremely small size ( approximately 1 nm diameter) renders their chemical and physical properties unique. A variety of different techniques are available for the production of SWCNT; however, the most common is via the disproportionation of gaseous carbon molecules supported on catalytic iron particles (high-pressure CO conversion, HiPCO). The physical nature of SWCNT may lead to dermal penetration following deposition on exposed skin. This dermal deposition provides a route of exposure which is important to consider when evaluating SWCNT toxicity. The dermal effects of SWCNT are largely unknown. We hypothesize that SWCNT may be toxic to the skin. We further hypothesize that SWCNT toxicity may be dependent upon the metal (particularly iron) content of SWCNT via the metal's ability to interact with the skin, initiate oxidative stress, and induce redox-sensitive transcription factors thereby affecting/leading to inflammation. To test this hypothesis, the effects of SWCNT were assessed both in vitro and in vivo using EpiDerm FT engineered skin, murine epidermal cells (JB6 P+), and immune-competent hairless SKH-1 mice. Engineered skin exposed to SWCNT showed increased epidermal thickness and accumulation and activation of dermal fibroblasts which resulted in increased collagen as well as release of pro-inflammatory cytokines. Exposure of JB6 P+ cells to unpurified SWCNT (30% iron) resulted in the production of ESR detectable hydroxyl radicals and caused a significant dose-dependent activation of AP-1. No significant changes in AP-1 activation were detected when partially purified SWCNT (0.23% iron) were introduced to the cells. However, NFkappaB was activated in a dose-dependent fashion by exposure to both unpurified and partially purified SWCNT. Topical exposure of SKH-1 mice (5 days, with daily doses of 40 microg/mouse, 80 microg/mouse, or 160 microug/mouse) to unpurified SWCNT caused oxidative stress, depletion of glutathione, oxidation of protein thiols and carbonyls, elevated myeloperoxidase activity, an increase of dermal cell numbers, and skin thickening resulting from the accumulation of polymorphonuclear leukocytes (PMNs) and mast cells. Altogether, these data indicated that topical exposure to unpurified SWCNT, induced free radical generation, oxidative stress, and inflammation, thus causing dermal toxicity.


Assuntos
Inflamação/induzido quimicamente , Nanotubos de Carbono/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Dermatopatias/induzido quimicamente , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Colágeno/metabolismo , Citocinas/biossíntese , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/imunologia , Glutationa/metabolismo , Humanos , Camundongos , Camundongos Pelados , NF-kappa B/biossíntese , NF-kappa B/genética , Oxazinas , Peroxidase/metabolismo , Pele/efeitos dos fármacos , Pele/metabolismo , Pele/patologia , Dermatopatias/patologia , Engenharia Tecidual , Fator de Transcrição AP-1/biossíntese , Fator de Transcrição AP-1/genética , Xantenos
3.
Cancer Res ; 61(22): 8051-7, 2001 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-11719426

RESUMO

Nickel compounds induce cell transformation in cell culture models and tumor formation in experimental animals. However, the molecular mechanisms by which nickel compounds induce tumors are not yet well understood. The present study found that exposure of cells to either Ni(3)S(2) or NiCl(2) could result in specific transactivation of nuclear factor of activated T cells (NFAT), although it did not show any activation of p53 or AP-1. Furthermore, nickel compounds were also able to cause generation of reactive oxygen species (ROS). The scavenging of nickel-induced H(2)O(2) with N-acety-L-cyteine (a general antioxidant) or catalase, or the chelation of nickel with deferoxamine, resulted in inhibition of NFAT activation. In contrast, pretreatment of cells with sodium formate (an .OH radical scavenger) or superoxide dismutase (an O(-.)(2) radical scavenger) did not show any inhibitory effects. These results demonstrate that nickel compounds are able to induce NFAT activation, and that the mechanism of NFAT activation seems to be mediated by the generation of H(2)O(2) by these metal compounds. This study should help us understand the signal transduction pathways involved in carcinogenic effects of these nickel compounds.


Assuntos
Carcinógenos/toxicidade , Proteínas de Ligação a DNA/fisiologia , Peróxido de Hidrogênio/metabolismo , Níquel/toxicidade , Proteínas Nucleares , Fatores de Transcrição/fisiologia , Ativação Transcricional/efeitos dos fármacos , Acetilcisteína/farmacologia , Animais , Calcineurina/metabolismo , Cálcio/metabolismo , Células Cultivadas , Quelantes/farmacologia , Ciclosporina/farmacologia , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/genética , Desferroxamina/farmacologia , Sinergismo Farmacológico , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Sequestradores de Radicais Livres/farmacologia , Camundongos , Fatores de Transcrição NFATC , Espécies Reativas de Oxigênio/metabolismo , Tapsigargina/farmacologia , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genética , Transfecção
4.
Oncogene ; 20(27): 3585-9, 2001 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-11429707

RESUMO

Growth arrest and DNA damage-inducible protein 45alpha (GADD45alpha) is an important cell cycle checkpoint protein that arrests cells at G2/M phase by inhibiting the activity of G2-specific kinase, cyclin B/p34cdc2. We report here that arsenite induces GADD45alpha expression in a p53-independent fashion and that this GADD45alpha induction by arsenite is regulated by NF-kappaB and c-Jun-N-terminal kinase (JNK) oppositely. In human bronchial epithelial cells overexpressing a kinase-mutated form of IkappaB kinase beta (IKKbeta-KM), the activation of NF-kappaB was inhibited. However, the G2/M cell cycle arrest and expression of GADD45alpha was substantially enhanced in response to arsenite in these cells. Expression of a dominant-negative mutant of SEK1 that blocks JNK activation decreased arsenite-induced GADD45alpha expression. Analysis of GADD45alpha expression in both wild-type and p53-/- fibroblasts indicated that the induction of GADD45alpha by arsenite was independent of the status of p53 protein.


Assuntos
Arsenitos/farmacologia , Ciclo Celular/fisiologia , Dano ao DNA , Regulação da Expressão Gênica/efeitos dos fármacos , MAP Quinase Quinase 4 , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Proteínas/genética , Mucosa Respiratória/fisiologia , Brônquios/citologia , Brônquios/fisiologia , Linhagem Celular , Ativação Enzimática , Fibroblastos/fisiologia , Fase G2 , Genes p53 , Humanos , Quinase I-kappa B , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Quinases JNK Ativadas por Mitógeno , Cinética , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Mitose , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Recombinantes/metabolismo , Mucosa Respiratória/citologia , Proteína Supressora de Tumor p53/metabolismo , Proteínas GADD45
5.
J Clin Endocrinol Metab ; 87(11): 5076-84, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12414875

RESUMO

Pituitary stalk interruption and ectopic posterior lobe on magnetic resonance imaging (MRI) are frequently observed in patients with GH deficiency (GHD), but their pathogenesis remains controversial. We performed pituitary stimulation tests, MRI, and studied GH-1, GHRH receptor (GHRH-R), and Prophet of Pit-1 (PROP-1) genes in 76 patients with GHD. Of 33 patients with isolated GHD, 4 had GH-1 deletions and 4 had GHRH-R mutations; of 43 patients with combined pituitary hormone deficiency, 1 had PIT-1 and 5 had PROP-1 mutations. Compared with the 62 patients without mutations, 14 patients with mutations had higher frequency of consanguinity (57 vs. 2%, P < 0.001), familial cases (21 vs. 3%, P < 0.05), and lower frequency of breech delivery or hypoxemia at birth (0 vs. 39%, P < 0.005). On MRI, all patients with mutations had an intact stalk, whereas it was interrupted or thin in 74% without mutations (P < 0.001). The posterior pituitary lobe was in normal position in 92% of patients with mutations against 13% without mutations (P < 0.001). Among patients with combined pituitary hormone deficiency, hormonal deficiencies were of pituitary origin in all with PROP-1 and PIT-1 mutations and suggestive of hypothalamic origin in 81% without mutations. Perinatal insults were associated with thin/interrupted pituitary stalk, ectopic posterior lobe, and hypothalamic origin of hormonal deficiencies. In contrast, GH-1, GHRH-R, and PROP-1 mutations were associated with consanguineous parents, intact pituitary stalk, normal posterior lobe, and pituitary origin of hormonal deficiencies. We conclude that pituitary MRI and hormonal response to stimulation tests are useful in selection of patients and candidate genes to elucidate the etiological diagnosis of GHD.


Assuntos
Proteínas de Homeodomínio/genética , Hormônio do Crescimento Humano/deficiência , Hormônio do Crescimento Humano/genética , Mutação , Hipófise/patologia , Receptores de Neuropeptídeos/genética , Receptores de Hormônios Reguladores de Hormônio Hipofisário/genética , Adolescente , Adulto , Criança , Pré-Escolar , Consanguinidade , Feminino , Deleção de Genes , Humanos , Hipotálamo/fisiopatologia , Lactente , Imageamento por Ressonância Magnética , Masculino , Hipófise/fisiopatologia , Neuro-Hipófise/patologia
6.
J Mol Neurosci ; 4(4): 263-75, 1993.
Artigo em Inglês | MEDLINE | ID: mdl-7917835

RESUMO

Antibodies to functional glutamate receptor subunits were utilized as probes to characterize glutamatergic receptors in human postmortem brain tissue. Crude membranes from rat, monkey, and various dissected human postmortem brain regions were fractionated by SDS-PAGE and electrotransferred to nitrocellulose. Using antisera raised against rat antigens for AMPA/kainate (GluR1-3) and kainate (GluR5) glutamate receptor subunits, we have been able to detect specific bands on Western blots in rat, monkey, and human postmortem brain tissue. These antisera recognized bands at approx 105 kDa for the GluR1-3 and 115 kDa for GluR5 in humans, monkeys, and rats. All of these glutamate receptor subtypes appear to be glycosylated. We observed varying levels of expression in the human brain areas examined, with the highest degree of expression in the hippocampus and temporal cortex for AMPA/kainate receptor subunits, and in the cortex and cerebellum for the kainate receptor subunits. In addition, considerable heterogeneity in expression was observed between protein, NCAM. Our studies indicate that glutamatergic receptor protein changes related to various human diseases states may be examined in human postmortem tissue by Western blotting techniques utilizing these antibodies raised to the rat protein.


Assuntos
Química Encefálica , Proteínas do Tecido Nervoso/análise , Receptores de Glutamato/análise , Adulto , Idoso , Animais , Western Blotting , Glicosilação , Haplorrinos , Humanos , Pessoa de Meia-Idade , Proteínas do Tecido Nervoso/classificação , Especificidade de Órgãos , Mudanças Depois da Morte , Ratos , Ratos Sprague-Dawley , Receptores de Glutamato/classificação , Especificidade da Espécie
7.
J Mol Neurosci ; 7(4): 277-89, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-8968949

RESUMO

Although glutamatergic receptors are localized throughout the mammalian central nervous system (CNS), the specific cellular localization of the various glutamatergic receptor subtypes throughout human brain remains largely unknown. PCR fragments to human GluR1, GluR2, and GluR3 receptor subtypes were cloned and used as probes for in situ hybridization in order to examine the anatomical and cellular localization of glutamate receptor subtype gene expression in dissected regions of human postmortem brain tissue. Although hybridization was observed throughout the CNS, results indicated that the highest levels of hybridization were in the hippocampus, with localization primarily to cells in the pyramidal cell layer of the CA1-CA3 region, and the granular cells of the dentate gyrus. Prominent hybridization also was observed in the medium to large neurons of the cingulate cortex, temporal lobe, septum, and amygdala, as well as in scattered neurons in the thalamus, cerebral cortex, and medulla. A striking pattern of differential hybridization was observed within the cerebellum. GluR1 demonstrated light hybridization along the Purkinje/Bergmann glia layer, with GluR2 and GluR3 demonstrating hybridization to Purkinje cells, and GluR3 also to cells within the molecular layer, previously identified as stellate-basket cells. Changes in glutamate receptor function have been shown to be important in the pathogenesis of a number of neurological disorders. Therefore, an examination of glutamatergic receptor expression in human postmortem brain tissue may provide important information on the molecular basis of a variety of neurological and psychiatric disorders of the CNS.


Assuntos
Encéfalo/metabolismo , Expressão Gênica , Mudanças Depois da Morte , Receptores de AMPA/biossíntese , Sequência de Bases , Tronco Encefálico/metabolismo , Cerebelo/metabolismo , Primers do DNA , Diencéfalo/metabolismo , Humanos , Hibridização In Situ , Mesencéfalo/metabolismo , Dados de Sequência Molecular , Sondas de Oligonucleotídeos , Especificidade de Órgãos , Reação em Cadeia da Polimerase , Telencéfalo/metabolismo
8.
Brain Res ; 674(1): 82-90, 1995 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-7773698

RESUMO

Antibodies to functional AMPA/kainate (GluR1, GluR2, GluR3), and kainate binding sites (GluR5-7) were used as probes to characterize and quantitate glutamatergic receptor subtypes in human post-mortem brain tissue from schizophrenic subjects and non-psychotic control subjects, which included normal controls and subjects with a previous history of alcohol abuse. Crude membrane fractions from human hippocampi and cingulate cortices were fractionated by SDS-PAGE, electrotransferred to nitrocellulose, and probed for the various glutamate receptor subtypes. Western blots were developed with chemiluminescence and the images analyzed by densitometry. Significant reductions were observed in the hippocampal immunoreactivity of both GluR2 and GluR3 AMPA/kainate receptor subtypes in schizophrenic subjects compared to the entire group of non-psychotic control subjects. No significant changes were observed in schizophrenic hippocampal GluR1 and GluR5 receptor subtypes or in levels of the structural control proteins, NCAM and tau. Significant increases were observed for GluR2 and GluR3 in the hippocampi of subjects with alcohol abuse histories when compared to the non-psychotic normal control group. When subjects with alcohol abuse histories were removed from the non-psychotic control pool, schizophrenics were no longer statistically different from the remaining normal controls. An analysis of GluR2 and GluR3 immunoreactivity in the cingulate cortex revealed no changes in these receptor subtypes among any of the groups. No alterations were observed in the immunoreactivity of these various proteins due to confounding factors such as age, sex, postmortem interval, or smoking history, except in the cingulate cortex were GluR3 receptor subtype levels were significantly reduced in the brains of smokers.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Alcoolismo/metabolismo , Encéfalo/metabolismo , Receptores de Glutamato/metabolismo , Esquizofrenia/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Western Blotting , Cadáver , Moléculas de Adesão Celular Neuronais/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Receptores de Glutamato/classificação , Proteínas tau/metabolismo
9.
Brain Res ; 825(1-2): 172-9, 1999 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-10216184

RESUMO

Tetracycline-regulated expression of recombinant nicotinic acetylcholine receptors (nAChR) composed of human alpha7 subunits is achieved in native nAChR-null SH-EP1 human epithelial cells. alpha7 subunits are heterologously expressed as messenger RNA and as components of 125I-labeled alpha-bungarotoxin (I-Bgt)-binding nAChR ( approximately 10 pmol per milligram of membrane protein) at levels sensitive to the amount of tetracycline in cell growth medium. I-Bgt-binding alpha7-nAChR appear on the cell surface pool and in intracellular pools. The pharmacological profile for drug competition toward I-Bgt binding to these recombinant alpha7-nAChR matches that of human native alpha7-nAChR naturally expressed in SH-SY5Y human neuroblastoma cells (rank order potency methyllycaconitine>1, 1-dimethyl-4-phenylpiperazinium>(-)nicotine>cytisine>carbamylch oli ne> /=d-tubocurarine). Chronic exposure to nicotine induces up-regulation of human recombinant alpha7-nAChR (80% up-regulation at 10 microM nicotine) just as it does native alpha7-nAChR in other human cell lines. These studies confirm expression of nAChR as homooligomers of human alpha7 subunits from transgenes, establish a native nAChR-null background for such expression, and demonstrate that this expression can be regulated to facilitate studies of human alpha7-nAChR.


Assuntos
Neuroblastoma , Neurônios/química , Neurônios/fisiologia , Receptores Nicotínicos/genética , Acetilcolina/fisiologia , Aconitina/análogos & derivados , Aconitina/farmacologia , Alcaloides/farmacologia , Azocinas , Northern Blotting , Bungarotoxinas/farmacologia , Carbacol/farmacologia , DNA Complementar , Iodeto de Dimetilfenilpiperazina/farmacologia , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/fisiologia , Humanos , Inseticidas/farmacologia , Radioisótopos do Iodo , Nicotina/farmacologia , Agonistas Nicotínicos/farmacologia , Plasmídeos , Inibidores da Síntese de Proteínas/farmacologia , Quinolizinas , RNA Mensageiro/análise , Receptores Nicotínicos/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Tetraciclina/farmacologia , Transfecção , Tubocurarina/farmacologia , Células Tumorais Cultivadas/química , Células Tumorais Cultivadas/citologia , Regulação para Cima/genética , Receptor Nicotínico de Acetilcolina alfa7
10.
Toxicology ; 150(1-3): 147-57, 2000 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-10996671

RESUMO

The present study investigated the generation of free radicals by wood smoke and cellular injuries caused by these radicals. Wood smoke was collected after thermolysis of western bark. Electron spin resonance (ESR) techniques were used to measure both carbon-centered radicals and generation of reactive oxygen species (ROS) by wood smoke. Wood smoke, in the presence of H(2)O(2), was found to be able to generate hydroxyl radical (.OH). DNA strand breakage was measured by exposing wood smoke to lambda Hind III fragments using gel electrophoresis. Wood smoke combined with H(2)O(2) caused DNA damage. Sodium formate, an .OH radical scavenger, or deferoxamine, a metal chelator, inhibited the DNA damage. Cellular DNA damage was also measured in cultured RAW 264.7 mouse macrophage cells by the single cell gel (SCG) electrophoresis assay. Cells were exposed to wood smoke samples for various times and significant DNA damage was observed. Elemental analysis was performed on the filter samples and the presence of Fe was noteworthy. Wood smoke is also able to cause lipid peroxidation, activate nuclear transcription factor, NFkappaB, and enhance the release of TNF-alpha from RAW 264. 7 cells. The results indicate that the free radicals generated by wood smoke through the reaction of Fe with H(2)O(2) are able to cause DNA and cellular damage and may act as a fibrogenic agent.


Assuntos
Dano ao DNA , Peroxidação de Lipídeos , Macrófagos/metabolismo , NF-kappa B/metabolismo , Fumaça/efeitos adversos , Fator de Necrose Tumoral alfa/biossíntese , Madeira , Animais , Linhagem Celular , Radical Hidroxila , Camundongos
11.
J Inorg Biochem ; 75(1): 37-44, 1999 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-10402675

RESUMO

Electrophoretic mobility shift, DNA strand breakage assays and electron spin resonance (ESR) spin trapping were used to investigate the activation of nuclear transcription factor (NF)-kappa B, DNA strand breakage and 2'-deoxyguanosine hydroxylation induced by Cr(IV), as well the role of free radical reactions in these processes. Incubation of synthesized Cr(IV)-glutathione complex with cultured Jurkat cells resulted in activation of DNA binding activity of NF-kappa B. Cr(VI) is also able to induce NF-kappa B activation through Cr(V) and Cr(IV) intermediates generated during the reduction of Cr(VI) by the cells. Cr(III) did not cause observable NF-kappa B activation due to its inability to cross cell membranes. Cr(IV)-induced NF-kappa B activation is dose-dependent. Catalase inhibited the activation while superoxide dismutase enhanced it. The metal chelator, deferoxamine, and hydroxyl (.OH) radical scavengers, sodium formate and aspirin, also inhibited the NF-kappa B activation. Electrophoretic assays using lambda Hind III linear DNA showed that, in the presence of H2O2, Cr(IV) is capable of causing DNA strand breaks. Deferoxamine, sodium formate and aspirin inhibited the DNA strand breaks. HPLC measurements also show that .OH radical generated by the Cr(IV)-mediated reaction with H2O2 was capable of causing 2'-deoxyguanosine (dG) hydroxylation to generate 8-hydroxyguanosine (8-OHdG). The relative magnitude of 8-OHdG formation correlated with the generation of .OH radicals. ESR spin trapping measurements showed that reaction of Cr(IV) with H2O2 generated .OH radicals, which were inhibited by deferoxamine, sodium formate and aspirin. The results show that Cr(IV) can cause NF-kappa B activation, DNA strand breaks and dG hydroxylation through .OH radical-initiated reactions. This reactive chromium intermediate may play an important role in the mechanism of Cr(VI)-induced carcinogenesis. The results also suggest that the Cr(IV)-glutathione complex may be used as a model compound to study the role of Cr(IV) in Cr(VI) carcinogenicity.


Assuntos
Carcinógenos/toxicidade , Cromo/toxicidade , Dano ao DNA , Desoxiguanosina/metabolismo , NF-kappa B/efeitos dos fármacos , Ativação Transcricional , Antioxidantes/uso terapêutico , Quelantes/uso terapêutico , Cromo/química , Espectroscopia de Ressonância de Spin Eletrônica , Eletroforese , Radicais Livres , Glutationa/química , Humanos , Hidroxilação , Células Jurkat
12.
J Environ Pathol Toxicol Oncol ; 19(3): 231-8, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10983889

RESUMO

Epidemiological studies demonstrate that environmental and occupational exposure of chromium(VI) [Cr(VI)] or Cr(VI)-containing particles can cause a number of human diseases, including inflammation and cancer. The biological mechanisms responsible for the initiation and progression of diseases resulting from exposure to Cr(VI) are not fully understood. The present studies evaluated the ability of Cr(IV) to induce activation of NF-kappaB and AP-1, two important transcription factors governing the expression of many early response genes involved in inflammation and carcinogenesis. The activation of NF-kappaB and AP-1 by Cr(IV) was dose dependent. Aspirin, a well-established antioxidant, substantially inhibited Cr(VI)-induced activation of both NF-kappaB and AP-1. SB202190, a specific inhibitor for p38, attenuated AP-1 activation induced by Cr(IV), whereas PD98059, a specific inhibitor for Erk, exhibited no effect on Cr(IV)-induced AP-1 activation. Blockage of NF-kappaB signaling pathway by a transient transfection of a dominant negative expressing vector for IkappaB kinase beta resulted in inhibition of Cr(IV)-induced NF-kappaB, but not AP-1 activation. These data suggest that the activation of AP-1 or NF-kappaB by Cr(IV) is through the involvement of MAP kinase or IKK pathway, respectively.


Assuntos
Cromatos/toxicidade , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Fator de Transcrição AP-1/metabolismo , Animais , Antioxidantes/farmacologia , Aspirina/farmacologia , Linhagem Celular , Cromatos/antagonistas & inibidores , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Fibroblastos/metabolismo , Flavonoides/farmacologia , Quinase I-kappa B , Imidazóis/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , NF-kappa B/biossíntese , NF-kappa B/genética , Piridinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Fator de Transcrição AP-1/biossíntese , Fator de Transcrição AP-1/genética , Transfecção , Proteínas Quinases p38 Ativadas por Mitógeno
13.
Ann Clin Lab Sci ; 30(2): 209-16, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10807167

RESUMO

Pyrrolidine dithiocarbamate (PDTC) is considered an antioxidant and is frequently used to study the role of free radical reactions in various biological processes and against free radical-induced cellular injuries. However, its antioxidant properties are not characterized. In this study, electron spin resonance (ESR) was used to investigate the antioxidant potential of PDTC with hydroxyl radical (*OH) and superoxide anion radicals (O2*-). The Fenton reaction [Fe(II) + H2O2 --> Fe(II) + *OH + OH-)] and xanthine and xanthine oxidase were used as sources of *OH and O2*- radicals, respectively. The results show that PDTC effectively scavenges *OH radicals with a reaction rate constant of approximately 2.73 x 10(10) M(-1) s(-1), which is comparable to other efficient *OH radical scavengers, such as ascorbate and glutathione. PDTC is also able to scavenge O2*- radicals. Through its antioxidant properties, PDTC protects against Cr(VI)-induced DNA strand breakage.


Assuntos
Antioxidantes/química , Cromo/química , Dano ao DNA/efeitos dos fármacos , Pirrolidinas/química , Tiocarbamatos/química , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Cromo/metabolismo , Cromo/farmacologia , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/química , Radicais Livres/metabolismo , Radical Hidroxila/química , Radical Hidroxila/metabolismo , Pirrolidinas/metabolismo , Pirrolidinas/farmacologia , Superóxidos/química , Superóxidos/metabolismo , Tiocarbamatos/metabolismo , Tiocarbamatos/farmacologia
14.
Ann Clin Lab Sci ; 29(3): 192-9, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10440583

RESUMO

Electron spin resonable (ESR) spin trapping with 5-(diethioxyphosphoyl)-5-methyl-1-pyrroline N-oxide (DEPMPO) was utilized to investigate the generation of oxygen free radicals from macrophages stimulated by tumor necrosis factor-alpha (TNF-alpha). TNF-alpha stimulated macrophages generated hydroxyl (*OH) and superoxide anion (O2*-) radicals. Incubation of TNF-alpha with macrophages resulted in an activation of DNA binding activity of the nuclear transcription factor NF-kappaB. Superoxide dismutase (SOD), but not catalase or sodium formate, inhibited this NF-kappaB activation, suggesting that O2*- rather than H2O2 or *OH, radicals play the most critical role in this induction. beta-Nicotinamide adenine dinucleotide phosphate (NADPH) did not affect the NF-kappaB activation, while allopurinol, an inhibitor of xanthine oxidase, repressed it, suggesting that xanthine/xanthine oxidase, and not NADPH dependent oxidase, may be a source of O2*- radicals which induce NF-kappaB activation. 02*- is generated via reduction of molecular oxygen by xanthine and xanthine oxidase, as demonstrated by the oxygen consumption assay. The results indicate that TNF-alpha induces oxygen radical generation from macrophages. 02*- seems to play a key role in TNF-alpha-induced NF-kappaB activation in macrophages. Xanthine and xanthine oxidase appears to be a source of O2*- radicals responsible for TNF-alpha-induced NF-kappaB activation.


Assuntos
Macrófagos/metabolismo , NF-kappa B/metabolismo , Superóxido Dismutase/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Linhagem Celular , Óxidos N-Cíclicos , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/metabolismo , Camundongos , Marcadores de Spin
15.
Ann Clin Lab Sci ; 27(5): 365-74, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9303176

RESUMO

While it is widely believed that taurine may play an important role in protecting cells against toxic injury by functioning as an antioxidant, there is a lack of evidence to support this hypothesis. In this study, electron spin resonance (ESR) was used to investigate the reaction of taurine and hypotaurine with hydroxyl radicals (.OH). The Fenton reaction (Fe(II) + H2O2-->Fe(III) + .OH + OH-) and the Cr(V)-mediated Fenton-like reaction (Cr(V) + H2O2-->Cr(VI) + .OH + OH-) were used as sources of .OH radicals. The results show that hypotaurine but not taurine effectively scavenges .OH radicals with a reaction rate constant of k = 1.6 x 10(10) M-1s-1. That is comparable with other efficient .OH radical scavengers. The effect of taurine and hypotaurine on silica-induced lipid peroxidation was evaluated using linoleic acid as a model lipid. Hypotaurine, but not taurine, caused a significant inhibition of silica-induced lipid peroxidation. The results show that hypotaurine is an excellent antioxidant and appears to have the potential for being a therapeutic agent against silica-induced lung injury.


Assuntos
Sequestradores de Radicais Livres/metabolismo , Radical Hidroxila/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Dióxido de Silício/farmacologia , Taurina/análogos & derivados , Taurina/metabolismo , Antioxidantes/química , Antioxidantes/metabolismo , Cromo/metabolismo , Óxidos N-Cíclicos/metabolismo , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres/metabolismo , Peróxido de Hidrogênio/metabolismo , Ferro/metabolismo , Cinética , Marcadores de Spin , Taurina/farmacologia , Ácido alfa-Linolênico/metabolismo
16.
Int J Poult Sci ; 13(2): 62-69, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-26180524

RESUMO

Phytogenic feed additives are plant-derived products used in poultry feeding to improve overall performance of broilers. In this study, 588 one day-old Cobb 500 chicks were fed one of four diets and housed on either dirty or clean litter for 3wks. Treatments included: Group I: commercial diet with no additive and housed on clean litter; Group II: commercial diet with no additive and housed on dirty litter; Group III: commercial diet with a 0.05% inclusion of the anitobiotic, BMD (bacitracin methylene disalicylate); Group IV: commercial diet with a 0.05% inclusion of a phytogenic feed additive (PFA). The study was designed around a random block assignment of treatments allocated to groups of twenty-one birds per pen. Blood samples were obtained from chicks at 18 days of age for measurement of leukocyte oxidative activity by a bioluminescence technique. Results of the study showed that chicks in the treatment groups fed the PFA had significantly lower oxidative stress (p<0.02) when compared to the BMD treatment group. Once this was determined, electron spin resonance (ESR) spin trapping was used to detect and measure hydroxyl or superoxide radicals in. Fenton chemistry was utilized for production of hydroxyl radicals and a xanthine/xanthine oxidase reaction for the production of superoxide radicals in the diet and in RAW 264.7 mouse peritoneal monocytes exposed to the diet. Results from the reactions showed that the antibiotic scavenges hydroxyl and superoxide radicals more efficiently than the phytogenic. The results were comparable to those measured in the RAW 264.7 cells.

17.
Mol Cell Biochem ; 222(1-2): 77-83, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11678614

RESUMO

Cr (VI) compounds are widely used in industries and are recognized human carcinogens. The mechanism of carcinogenesis associated with these compounds is not well understood. The present study focused on Cr (VI)-induced cell growth arrest in human lung epithelial A549 cells, using flow cytometric analysis of DNA content. Treatment of the cells with Cr (VI) at 1 microM caused a growth arrest at G2/M phase. An increase in Cr (VI) concentration enhanced the growth arrest. At a concentration of 25 microM, Cr (VI)-induced apoptosis became apparent. Superoxide dismutase (SOD) or sodium formate did not alter the Cr (VI)-induced cell growth arrest. While catalase inhibited growth, indicating H2O2 is an important mediator in Cr (VI)-induced G2/M phase arrest. Electron spin resonance (ESR) spin trapping measurements showed that incubation of cells with Cr (VI) generated hydroxyl radical (*OH). Catalase inhibited the *OH radical generation, indicating that H2O2 was generated from cells stimulated by Cr (VI), and that H2O2 functioned as a precursor for *OH radical generation. The formation of H2O2 from Cr (VI)-stimulated cells was also measured by the change in fluorescence of scopoletin in the presence of horseradish peroxidase. The mechanism of reactive oxygen species generation involved the reduction of molecular oxygen as shown by oxygen consumption assay. These results support the following conclusions: (a) Reactive oxygen species are generated in Cr (VI)-stimulated A549 cells through reduction of molecular oxygen, (b) Among the reactive oxygen species generated, H2O2 played a major role in causing G2/M phase arrest in human lung epithelial cells.


Assuntos
Carcinógenos Ambientais/farmacologia , Cromo/farmacologia , Peróxido de Hidrogênio/metabolismo , Radical Hidroxila/metabolismo , Antioxidantes/farmacologia , Apoptose , Carcinógenos Ambientais/metabolismo , Catalase/farmacologia , Ciclo Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Cromo/metabolismo , Interações Medicamentosas , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/patologia , Humanos , Pulmão/citologia , Consumo de Oxigênio/efeitos dos fármacos , Consumo de Oxigênio/fisiologia , Células Tumorais Cultivadas
18.
Am J Physiol Cell Physiol ; 279(3): C868-75, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-10942736

RESUMO

The present study investigates whether reactive oxygen species (ROS) are involved in p53 activation, and if they are, which species is responsible for the activation. Our hypothesis is that hydroxyl radical (.OH) functions as a messenger for the activation of this tumor suppressor protein. Human lung epithelial cells (A549) were used to test this hypothesis. Cr(VI) was employed as the source of ROS due to its ability to generate a whole spectrum of ROS inside the cell. Cr(VI) is able to activate p53 by increasing the protein levels and enhancing both the DNA binding activity and transactivation ability of the protein. Increased cellular levels of superoxide radicals (O(2)(-).), hydrogen peroxide (H(2)O(2)), and.OH radicals were detected on the addition of Cr(VI) to the cells. Superoxide dismutase, by enhancing the production of H(2)O(2) from O(2)(-). radicals, increased p53 activity. Catalase, an H(2)O(2) scavenger, eliminated.OH radical generation and inhibited p53 activation. Sodium formate and aspirin,.OH radical scavengers, also suppressed p53 activation. Deferoxamine, a metal chelator, inhibited p53 activation by chelating Cr(V) to make it incapable of generating radicals from H(2)O(2). NADPH, which accelerated the one-electron reduction of Cr(VI) to Cr(V) and increased.OH radical generation, dramatically enhanced p53 activation. Thus.OH radical generated from Cr(VI) reduction in A549 cells is responsible for Cr(VI)-induced p53 activation.


Assuntos
Carcinógenos Ambientais/farmacologia , Cromo/farmacologia , Radical Hidroxila/metabolismo , Sistemas do Segundo Mensageiro/fisiologia , Proteína Supressora de Tumor p53/fisiologia , Linhagem Celular , Relação Dose-Resposta a Droga , Radicais Livres/metabolismo , Humanos , Consumo de Oxigênio , Fatores de Tempo
19.
Mol Cell Biochem ; 206(1-2): 125-32, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10839202

RESUMO

Electron spin resonance (ESR) spin trapping was utilized to investigate the scavenging effects on hydroxyl radicals (*OH) and superoxide radicals (O2*-) by (-)-epigallocatechin-3-gallate (EGCG), one of the major anticancer compounds in tea. The spin trap used was 5,5-dimethyl-pyrroline N-oxide (DMPO). The Fenton reaction (Fe2+ + H2O2-->Fe3+ + *OH + OH-) was used as a source of *OH radicals. EGCG efficiently scavenges *OH radicals with reaction rate of 4.62 x 10(11) M(-1)sec(-1), which is an order of magnitude higher than several well recognized antioxidants, such as ascorbate, glutathione and cysteine. It also scavenges O2*- radicals as demonstrated by using xanthine and xanthine oxidase system as a source of O2*- radicals. Through its antioxidant properties, EGCG exhibited a protective effect against DNA damage induced by Cr(VI). EGCG also inhibited activation of nuclear transcription factor NF-kappaB induced by Cr(IV) and 12-o-tetradecanoylphorbol-13-acetate (TPA). The present studies provide a mechanistic basis for the reported anticarcinogenic properties of EGCG and related tea products.


Assuntos
Antioxidantes/farmacologia , Catequina/análogos & derivados , Catequina/farmacologia , Cromatos/antagonistas & inibidores , Cromo/antagonistas & inibidores , Dano ao DNA/efeitos dos fármacos , NF-kappa B/metabolismo , Acetato de Tetradecanoilforbol/antagonistas & inibidores , Células Cultivadas , Cromatos/farmacologia , Cromo/farmacologia , Espectroscopia de Ressonância de Spin Eletrônica , Eletroforese em Gel de Poliacrilamida , Sequestradores de Radicais Livres , Humanos , Radical Hidroxila/metabolismo , Células Jurkat/metabolismo , Superóxidos/metabolismo , Acetato de Tetradecanoilforbol/farmacologia
20.
Exp Mol Pathol ; 66(3): 201-10, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10486238

RESUMO

Asbestos exposure in humans is associated with inflammatory, fibrotic, and malignant diseases in the lung. Increasing evidence supports the hypothesis that the production of proinflammatory cytokines such as tumor necrosis factor-alpha (TNFalpha) is an important mediator of the pathologic responses of asbestosis. In this study, we examine the role of nuclear transcription factor-kappaB (NF-kappaB) and free oxygen radicals in asbestos-induced TNFalpha gene and protein expression in lung macrophages. Exposure of the cells to crocidolite asbestos caused a parallel increase in TNFalpha production and NF-kappaB activation, as analyzed by enzyme-linked immunosorbent assay and electrophoretic mobility shift assay. Inhibition of NF-kappaB by SN50, an inhibitor of NF-kappaB nuclear translocation, or by sequence-specific oligonucleotides directed against the NF-kappaB binding site of TNFalpha promoter attenuated the asbestos effect on TNFalpha production. Gene transfection assays using an expression plasmid containing a luciferase reporter gene and a TNFalpha-derived NF-kappaB gene promoter further indicated the dependence of NF-kappaB activation on asbestos-induced gene expression. The effects of asbestos on NF-kappaB and TNFalpha activation were inhibited by oxygen radical scavengers and were enhanced by antioxidant enzyme inhibitors. These results indicate that asbestos-induced TNFalpha gene expression is mediated through a process that involves NF-kappaB activation and free radical reactions.


Assuntos
Asbesto Crocidolita/toxicidade , Macrófagos Alveolares/efeitos dos fármacos , NF-kappa B/metabolismo , Fator de Necrose Tumoral alfa/biossíntese , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Ensaio de Imunoadsorção Enzimática , Sequestradores de Radicais Livres/farmacologia , Expressão Gênica/efeitos dos fármacos , Luciferases/análise , Luciferases/biossíntese , Luciferases/genética , Luciferases/metabolismo , Macrófagos Alveolares/metabolismo , Masculino , NF-kappa B/antagonistas & inibidores , Peptídeos/farmacologia , Ratos , Ratos Sprague-Dawley , Superóxidos/metabolismo , Transfecção
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