RESUMO
The work presented herein displays the results of a study addressing environmental concerns related to the possible leaching of pollutants from reclaimed asphalt pavement. Samples from an experimental site were tested in both static batch tests and column leaching tests. Selected heavy metals and polycyclic aromatic hydrocarbons (PAHs) were analysed in leachates. The results have allowed us to consider the leaching of pollutants to be rather weak for most of the parameters studied. Concentrations in solutions from batch leaching tests were generally below the EC limit values for drinking water. Pollutant concentrations from column experiments were higher in solutions as of the initial leaching stages, but then decreased rapidly and wound up at values below the detection limits. The factors influencing results proved to be the material grain size and the percolation water flow rate. Results from leaching experiments performed on core samples taken on two rebuilt road section pavements, containing 10% and 20% of reclaimed asphalt pavement, respectively, confirmed the results obtained from the batch and column experiments.
Assuntos
Conservação dos Recursos Naturais , Hidrocarbonetos , Metais Pesados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Hidrocarbonetos/química , Movimentos da ÁguaRESUMO
Previous research has demonstrated the ability of the Cognitive Behavioral Driver's Inventory (CBDI) to detect neuropsychological malingering [Arch. Clin. Neuropsychol. 12 (5) (1997) 491.], however, the present study tests if the CBDI can discern malingerers when they are "coached" on how brain-damaged patients actually perform on neuropsychological tests. Ninety-eight college student participants were given financial incentive to fake brain damage on the CBDI. Fifty-three of these subjects were "coached" and 45 were not. The coached and uncoached subjects performed indistinguishably on the CBDI. Both types of malingerers were discernable from real brain-damaged patients (99.2% accuracy area under the sensitivity-specificity curve). Further, CBDI profiles of five actual plaintiffs judged to be malingering were compared to CBDI profiles of experimental subjects. In each case, the malingering plaintiff's CBDI profile was indistinguishable from that of malingering experimental subjects and was clearly discernable from that of actual brain-damaged patients.
Assuntos
Lesões Encefálicas/complicações , Transtornos Cognitivos/diagnóstico , Simulação de Doença/diagnóstico , Prática Psicológica , Adulto , Transtornos Cognitivos/etiologia , Feminino , Humanos , Masculino , Motivação , Testes Neuropsicológicos , Valor Preditivo dos Testes , Psicometria , Reprodutibilidade dos Testes , Análise e Desempenho de TarefasRESUMO
We have developed a cell culture of guinea pig gallbladder epithelial cells with which to study ion transport. When grown on permeable supports, the cultured epithelia developed a transepithelial resistance (R(t)) of approximately 500 Omega. cm(2). The epithelial cell origin of the cell culture was further confirmed by immunocytochemical localization of cytokeratin. Ionomycin and forskolin increased transepithelial voltage and short-circuit current (I(sc)) and decreased R(t). The response to ionomycin was transient, whereas that to forskolin was sustained. Both were attenuated by replacement of Cl(-) and/or HCO(3)(-). Mucosal addition of the anion transport inhibitors DIDS or diphenylamine-2-carboxylic acid (DPC) blocked the response to ionomycin. The response to forskolin was blocked by DPC but not by DIDS. Ionomycin, but not forskolin, increased intracellular Ca(2+) concentration in fura 2-loaded cells. PGE(2), histamine, vasoactive intestinal polypeptide, and secretin elicited a sustained increase in I(sc). Responses to ATP and CCK were transient. Thus cultured guinea pig gallbladder epithelia display the range of responses observed in the native tissue and are an appropriate model for studies of ion transport in gallbladder and intestinal epithelia.
Assuntos
Células Epiteliais/citologia , Células Epiteliais/metabolismo , Vesícula Biliar/citologia , Fármacos Gastrointestinais/farmacologia , Peptídeo Intestinal Vasoativo/farmacologia , Ácido 4,4'-Di-Isotiocianoestilbeno-2,2'-Dissulfônico/farmacologia , Trifosfato de Adenosina/farmacologia , Animais , Ânions/metabolismo , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Cálcio/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Células Cultivadas , Colecistocinina/farmacologia , Colforsina/farmacologia , AMP Cíclico/metabolismo , Dinoprostona/farmacologia , Células Epiteliais/efeitos dos fármacos , Cobaias , Histamina/farmacologia , Ionomicina/farmacologia , Ionóforos/farmacologia , Masculino , Secretina/farmacologia , ortoaminobenzoatos/farmacologiaRESUMO
Using an affinity resin and photoaffinity label based on phospholipid analogs of inositol 1,3,4,5-tetrakisphosphate (InsP4), we have isolated, characterized, and cloned a 46-kDa protein from rat brain, which we have named centaurin-alpha. Binding specificity was determined using displacement of 1-O-[3H](3-[4-benzoyldihydrocinnamidyl]propyl)-InsP4 photoaffinity labeling. Centaurin-alpha displayed highest affinity for phosphatidylinositol 3,4,5-trisphosphate (PtdInsP3) (IC50 = 120 nM), whereas InsP4, PtdInsP2, and InsP3 bound with 5-, 12-, and >50-fold lower affinity, respectively. Screening a rat brain cDNA library with a polymerase chain reaction product, generated using partial amino acid sequence from tryptic peptides, yielded a full-length clone. The 2,450-base pair cDNA contained an open reading frame (ORF) encoding a novel protein of 419 amino acids. Northern analysis revealed a 2.5-kilobase transcript that is highly expressed in brain. The deduced sequence contains a novel putative zinc finger motif, 10 ankyrin-like repeats, and shows homology to recently identified yeast and mammalian Arf GTPase-activating proteins. Given the specificity of binding and enrichment in brain, centaurin-alpha is a candidate PtdInsP3 receptor that may link the activation of phosphoinositide 3-kinase to downstream responses in the brain.
Assuntos
Encéfalo/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Sequência de Aminoácidos , Animais , Anquirinas/genética , Sequência de Bases , Linhagem Celular , Clonagem Molecular , Sequência Conservada , DNA Complementar/genética , Proteínas Ativadoras de GTPase , Humanos , Dados de Sequência Molecular , Ratos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , TransfecçãoRESUMO
Application of nerve growth factor (NGF) to PC12 cells stimulates a programme of physiological changes leading to the development of a sympathetic neuron like phenotype, one aspect of which is the development of a neuronal morphology characterised by the outgrowth of neuritic processes. We have investigated the role of phosphoinositide 3-kinase in NGF-stimulated morphological differentiation through two approaches: firstly, preincubation with wortmannin, a reputedly specific inhibitor of phosphoinositide kinases, completely inhibited initial morphological responses to NGF, the formation of actin filament rich microspikes and subsequent neurite outgrowth. This correlated with wortmannin inhibition of NGF-stimulated phosphatidylinositol(3,4,5)trisphosphate (PtdInsP3) and phosphatidylinositol(3,4)bisphosphate (PtdIns(3,4)P2) production and with inhibition of NGF-stimulated phosphoinositide 3-kinase activity in anti-phosphotyrosine immunoprecipitates. Secondly, the overexpression of a mutant p85 regulatory subunit of the phosphoinositide 3-kinase, which cannot interact with the catalytic p110 subunit, also substantially inhibited the initiation of NGF-stimulated neurite outgrowth. In addition, we found that wortmannin caused a rapid collapse of more mature neurites formed following several days exposure of PC12 cells to NGF. These results indicate that NGF-stimulated neurite outgrowth requires the activity of a tyrosine kinase regulated PI3-kinase and suggest that the primary product of this enzyme, PtdInsP3, is a necessary second messenger for the cytoskeletal and membrane reorganization events which occur during neuronal differentiation.