RESUMO
In order to encourage increased rates in respect of sorting, recycling and the diversion of construction and demolition waste (C&DW), the world's more advanced economies have developed innovative new technologies and studies to improve the creation of sustainable societies. To achieve this, it is important to dedicate greater efforts to the elaboration of tariff schemes and studies to determine society's disposition to improve the management of C&DW. This study analyzes willingness of construction companies in Chile to pay (WTP) to improve the C&DW management, through the contingent valuation method (CVM). This aims to provide analytical background and market information to circular business models and, in turn, provide information which can be used to define public policies governing the subject, as a contribution to future regulatory developments. The Chilean construction industry was surveyed and a total of 57 valid questionnaires were collected. The results show that the average WTP for inert C&DW, non-inert C&DW, mixed C&DW with a greater quantity of inert waste and mixed C&DW with a greater quantity of non-inert waste was 8.77 (US $/ton), 7.73 (US $/ton), 7.98 (US $/ton) and 8.22 (US $/ton), respectively. Additionally, the cost of waste removal and disposal had an average value of 9.68 (US $/ton). Through multiple regression analysis, it was discovered that the variables related to knowledge about circular economy, state actions, management of C&DW and productivity have a significant effect on WTP. These results provide new evidence for the development of appropriate public policies to address the problem of C&DW and improve management in Chile.
Assuntos
Indústria da Construção , Gerenciamento de Resíduos , Chile , Materiais de Construção , Resíduos Industriais , ReciclagemRESUMO
Nasal olfactory stem and neural progenitor cells (NOS/PCs) are considered possible tools for regenerative stem cell therapies in neurodegenerative diseases. Neurogenesis is a complex process regulated by extrinsic and intrinsic signals that include DNA-methylation and other chromatin modifications that could be experimentally manipulated in order to increase neuronal differentiation. The aim of the present study was the characterization of primary cultures and consecutive passages (P2-P10) of NOS/PCs isolated from male Swiss-Webster (mNOS/PCs) or healthy humans (hNOS/PCs). We evaluated and compared cellular morphology, proliferation rates and the expression pattern of pluripotency-associated markers and DNA methylation-associated gene expression in these cultures. Neuronal differentiation was induced by exposure to all-trans retinoic acid and forskolin for 7 days and evaluated by morphological analysis and immunofluorescence against neuronal markers MAP2, NSE and MAP1B. In response to the inductive cues mNOS/PCs expressed NSE (75.67%) and MAP2 (35.34%); whereas the majority of the hNOS/PCs were immunopositive to MAP1B. Treatment with procainamide, a specific inhibitor of DNA methyltransferase 1 (DNMT1), increases in the number of forskolin'/retinoic acid-induced mature neuronal marker-expressing mNOS/PCs cells and enhances neurite development in hNOS/PCs. Our results indicate that mice and human nasal olfactory stem/progenitors cells share pluripotency-related gene expression suggesting that their application for stem cell therapy is worth pursuing and that DNA methylation inhibitors could be efficient tools to enhance neuronal differentiation from these cells.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Colforsina/farmacologia , DNA (Citosina-5-)-Metiltransferases/metabolismo , Células-Tronco Neurais/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Mucosa Olfatória/citologia , Tretinoína/farmacologia , Animais , Células Cultivadas , DNA (Citosina-5-)-Metiltransferase 1 , Metilação de DNA/efeitos dos fármacos , Humanos , Masculino , Camundongos , Proteínas do Tecido Nervoso/metabolismo , Fatores de TempoRESUMO
Aging increases the vulnerability to stress and risk of developing depression. These changes have been related to a reduction of dehydroepiandrosterone (DHEA) levels, an adrenal steroid with anti-stress effects. Also, adult hippocampal neurogenesis decreases during aging and its alteration or impaired is related to the development of depression. Besides, it has been hypothesized that DHEA increases the formation of new neurons. However, it is unknown whether treatment with DHEA in aging may stimulate the dendrite maturation of newborn neurons and reversing depressive-like signs evoked by chronic stress exposure. Here aged male rats (14 months old) were subjected to a scheme of chronic mild stress (CMS) during six weeks, received a treatment with DHEA from the third week of CMS. Changes in body weight and sucrose preference (SP) were measured once a week. DHEA levels were measured in serum, identification of doublecortin-(DCX)-, BrdU- and BrdU/NeuN-labeled cells was done in the dentate gyrus of the hippocampus. CMS produced a gradual reduction in the body weight, but no changes in the SP were observed. Treatment enhanced levels of DHEA, but lack of recovery on body weight of stressed rats. Aging reduced the number of DCX-, BrdU- and BrdU/NeuN- cells but DHEA just significantly increased the number of DCX-cells in rats under CMS and controls, reaching levels of young non-stressed rats (used here as a reference of an optimal status of health). In rats under CMS, DHEA facilitated dendritic maturation of immature new neurons. Our results reveal that DHEA improves neural plasticity even in conditions of CMS in middle age rats. Thus, this hormone reverted the decrement of DCX-cells caused during normal aging.
Assuntos
Envelhecimento/efeitos dos fármacos , Desidroepiandrosterona/farmacologia , Dendritos/efeitos dos fármacos , Giro Denteado/efeitos dos fármacos , Psicotrópicos/farmacologia , Estresse Psicológico/tratamento farmacológico , Envelhecimento/fisiologia , Envelhecimento/psicologia , Animais , Antígenos Nucleares/metabolismo , Peso Corporal/efeitos dos fármacos , Bromodesoxiuridina , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Doença Crônica , Desidroepiandrosterona/sangue , Dendritos/metabolismo , Dendritos/patologia , Giro Denteado/metabolismo , Giro Denteado/patologia , Sacarose Alimentar , Proteínas do Domínio Duplacortina , Proteína Duplacortina , Masculino , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/efeitos dos fármacos , Neurogênese/fisiologia , Neuropeptídeos/metabolismo , Psicotrópicos/sangue , Distribuição Aleatória , Ratos Wistar , Estresse Psicológico/metabolismo , Estresse Psicológico/patologiaRESUMO
Epigallo-catechin-3-gallate (EGCG), found in the leaves of Camellia sinensis (green tea), has antioxidant- and scavenger-functions and acts neuroprotectively. It has been publicized as anti-aging remedy but data on potential cellular mechanisms are scarce. Recent studies claimed that EGCG specifically promotes neural precursor cell proliferation in the dentate gyrus of C57Bl/6 mice, without changes at the level of immature and mature new neurons. We here analyzed the effects of EGCG on adult hippocampal neurogenesis in male Balb/C mice and saw a different pattern. Two weeks of treatment with EGCG (0, 0.625, 1.25, 2.5, 5 and 10mg/kg) showed a dose-response curve that peaked at 2.5mg/kg of EGCG with significantly increased cell survival without affecting cell proliferation but decreasing apoptotic cells. Also, EGCG increased the population of doublecortin-(DCX)-expressing cells that comprises the late intermediate progenitor cells (type-2b and -3) as well as immature neurons. After EGCG treatment, the young DCX-positive neurons showed more elaborated dendritic trees. EGCG also significantly increased net neurogenesis in the adult hippocampus and increased the hippocampal levels of phospho-Akt. Ex vivo, EGCG exerted a direct effect on survival and neuronal differentiation of adult hippocampal precursor cells, which was absent, when PI3K, a protein upstream of Akt, was blocked. Our results thus support a pro-survival and a pro-neurogenic role of EGCG. In the context of the conflicting published results, however, potential genetic modifiers must be assumed. These might help to explain the overall variability of study results with EGCG. Our data do indicate, however, that natural compounds such as EGCG can in principle modulate brain plasticity.
Assuntos
Catequina/análogos & derivados , Sobrevivência Celular/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Neurogênese/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Animais , Catequina/química , Catequina/farmacologia , Sobrevivência Celular/fisiologia , Células Cultivadas , Relação Dose-Resposta a Droga , Proteínas do Domínio Duplacortina , Proteína Duplacortina , Hipocampo/fisiologia , Masculino , Camundongos Endogâmicos BALB C , Proteínas Associadas aos Microtúbulos/metabolismo , Células-Tronco Neurais/efeitos dos fármacos , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Neurônios/fisiologia , Neuropeptídeos/metabolismo , Fármacos Neuroprotetores/química , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Chá/químicaRESUMO
Brain imaging and histopathological studies suggest that neurodevelopmental anomalies play a key role in the etiology of schizophrenia (SZ) and bipolar disorder (BD). New neuron formation and maturation occur in human olfactory epithelium throughout life. Therefore, the olfactory epithelium has been proposed as a model to study alterations in neurodevelopment, particularly in some psychiatric diseases. However, former studies were done with olfactory epithelium biopsies taken post mortem or under anesthesia from patients with SZ and BD. In this work we have developed a new method to obtain viable neural precursors by exfoliation of the anterior region of the medial lateral turbinate of the nasal cavity from healthy controls, and ambulatory patients. Cells were propagated to establish neural precursor banks. Thawed cells showed cytoskeletal phenotypes typical of developing neurons. They also conserved the ability to differentiate in presence of 2mM dibutyril-cyclic adenosine monophosphate, and maintained voltage-operated Ca(2+) currents in culture. Moreover, proportions of neuronal maturation stages were maintained in cultured exfoliates obtained from SZ and BD patients. Data support that neural precursors obtained from a nasal exfoliate are an excellent experimental model to later approach studies on biomarkers, neural development and cellular alterations in the pathophysiology of SZ and BD.