RESUMEN
Xylem is the main tissue for water transport in plants, and the changes of hydraulic properties in which would affect plant water relations and fruit water accumulation. It remains unclear regarding the responses of xylem anatomy and hydraulic properties to water and salt stresses in tomato plants and their relationships with plant growth and fruit water content. We conducted a pot experiment in a greenhouse to investigate the responses of plant growth, fruit water content, and xylem hydraulic properties of a cherry tomato (Hong Baoshi) and a medium-fruited tomato (Beifan 501). There were three treatments, control with a soil water content (θ) of 75%-95% of field capacity (FC) and an initial electrical conductivity (EC) of 0.398 dS·m-1; water stress with θ of 75%-95% of FC (before flowering) and 45%-65% of FC (from flowering until maturity) and an EC of 0.398 dS·m-1; and salt stress with θ of 75%-95% of FC and an EC of 1.680 dS·m-1. Results showed that water and salt stresses decreased the cross-sectional stem area and xylem vessel diameter by 22.0%-40.7% and 10.0%-18.3%, respectively, and reduced the specific hydraulic conductivity of stem and the hydraulic conductivity of peduncle by 8.8%-41.1% and 12.9%-28.4%, respectively. Those changes inhibited plant growth and reduced aboveground fresh weight, fruit size, fresh weight and water content, with a more pronounced negative effect in the medium-fruited tomato. More-over, fruit water content was positively correlated with the specific hydraulic conductivity of stem and peduncle. In conclusion, water and salt stresses would inhibit plant growht, fruit fresh weight, and consequently tomato yield, due to their negative effects on xylem hydraulic properties of the tomato plant. Medium-fruited tomatoes are more susceptible to water and salt stresses than cherry tomatoes.
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Solanum lycopersicum , Estudios Transversales , Xilema/fisiología , Suelo , Estrés Salino , Hojas de la Planta/fisiologíaRESUMEN
Background: A new goal in treatment of chronic myeloid leukemia (CML) in patients with stable deep molecular response (DMR) is maintaining durable treatment-free remission (TFR) after discontinuing tyrosine kinase inhibitor (TKI) treatment. Methods: We conducted a systematic review and meta-analysis focusing on the efficacy and safety of TKI discontinuation but also exploring the factors contributing to successful TFR. Results: The search yielded 10 trials including 1,601 patients. For patients who discontinued TKIs, the estimated weighted mean incidence of major molecular relapse was 16% (95%CI: 11-21), 34% (95%CI: 29-38), 39% (95%CI: 35-43) and 41% (95%CI: 36-47) at 3, 6, 12, and 24 months, respectively. Of these, 39, 82, and 95% of molecular losses occurred within the first 3, 6, and 12 months. In safety analysis, among patients without TFR, 98% (95% CI: 96-100) were sensitive to TKI retreatment. No new safety issues were identified except TKI withdrawal syndrome, which appeared during the early TFR phase, with a weighted mean incidence of 27% (95%CI: 19-35). Our subgroup analysis suggested better TFR associated with interferon therapy (P = 0.007), depth of molecular response (P = 0.018) and duration of DMR (P < 0.001). Conclusions: TFR as an extension of an approach to optimize management of CML is clinically feasible in approximately 59% of patients with sufficient TKI response. In the remaining 41% of patients with molecular relapse, discontinuing TKIs had no negative impact on clinical outcomes. Given the high heterogeneity among studies, the role of these predictors for successful TFR still requires further investigation.
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OBJECTIVES: With bosutinib proven to be available for frontline treatment, there are currently four frontline treatments as well as an additional strategy with high-dose imatinib for newly diagnosed chronic myeloid leukemia (CML). Due to the lack of direct comparison of high-dose imatinib, dasatinib, nilotinib, and bosutinib, we summarized the evidence to indirectly compare the efficacy among these treatment options. METHODS: In total, 14 randomized clinical trials including 5,630 patients were analyzed by direct and mixed-treatment comparisons. Outcomes assessed were the following: complete cytogenetic response at 12 months; major molecular response at 12, 24, and 36 months; deep molecular response at 12, 24, 36, and 60 months; early molecular response at 3 months; progression-free survival (PFS); overall survival (OS); and Grade 3 or 4 adverse events (AEs). RESULTS: The Bayesian network meta-analysis demonstrated that high-dose imatinib was less effective than all new-generation tyrosine kinase inhibitors and had a higher probability of Grade 3 or 4 AEs. For molecular response, 300 mg of nilotinib was likely to be the preferred frontline treatment, as demonstrated by higher response rates and faster, deeper, and longer molecular response. For PFS and OS, there were high likelihoods (79% and 74%, respectively) that 400 mg of nilotinib was the preferred option. For AEs, standard-dose imatinib has the highest probability (65%) of being the most favorable toxicity profile. CONCLUSION: Considering the efficacy and toxicity profile, it is not recommended to use high-dose imatinib for treatment. This analysis also showed that nilotinib has the highest probability to become the preferred frontline agents for treating CML.
RESUMEN
BACKGROUND: Dengue remains an important public health problem in Timor-Leste, with several major epidemics occurring over the last 10 years. The aim of this study was to identify dengue clusters at high geographical resolution and to determine the association between local environmental characteristics and the distribution and transmission of the disease. METHODS: Notifications of dengue cases that occurred from January 2005 to December 2013 were obtained from the Ministry of Health, Timor-Leste. The population of each suco (the third-level administrative subdivision) was obtained from the Population and Housing Census 2010. Spatial autocorrelation in dengue incidence was explored using Moran's I statistic, Local Indicators of Spatial Association (LISA), and the Getis-Ord statistics. A multivariate, Zero-Inflated, Poisson (ZIP) regression model was developed with a conditional autoregressive (CAR) prior structure, and with posterior parameters estimated using Bayesian Markov chain Monte Carlo (MCMC) simulation with Gibbs sampling. RESULTS: The analysis used data from 3206 cases. Dengue incidence was highly seasonal with a large peak in January. Patients ≥ 14 years were found to be 74% [95% credible interval (CrI): 72-76%] less likely to be infected than those < 14 years, and females were 12% (95% CrI: 4-21%) more likely to suffer from dengue as compared to males. Dengue incidence increased by 0.7% (95% CrI: 0.6-0.8%) for a 1 °C increase in mean temperature; and 47% (95% CrI: 29-59%) for a 1 mm increase in precipitation. There was no significant residual spatial clustering after accounting for climate and demographic variables. CONCLUSIONS: Dengue incidence was highly seasonal and spatially clustered, with positive associations with temperature, precipitation and demographic factors. These factors explained the observed spatial heterogeneity of infection.
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Dengue/epidemiología , Análisis Espacio-Temporal , Topografía Médica , Factores de Edad , Humanos , Incidencia , Estaciones del Año , Factores Sexuales , Temperatura , Timor Oriental/epidemiologíaRESUMEN
Copper (Cu) has a critical role in the generation of oxidative stress during neurodegeneration and cancer. Reactive oxygen species generated through abnormal elevation or deficiency of Cu can lead to lipid, protein, and DNA damage. Oxidation of DNA can induce strand breaks and is associated with altered cell fate including transformation or death. DNA repair is mediated through the action of the multimeric DNA-PK repair complex. The components of this complex are the Ku autoantigens, XRCC5 and XRCC6 (Ku80 and Ku70, respectively). How this repair complex responds to perturbed Cu homeostasis and Cu-mediated oxidative stress has not been investigated. We previously reported that XRCC5 expression is altered in response to cellular Cu levels, with low Cu inhibiting XRCC5 expression and high Cu levels enhancing expression. In this study we further investigated the interaction between XRCC5 and Cu. We report that cytosolic XRCC5 is increased in response to Cu, but not zinc, iron, or nickel, and the level of cytosolic XRCC5 correlates with protection against oxidative damage to DNA. These observations were made in both HeLa cells and fibroblasts. Cytosolic XRCC5 interacted with the Cu chaperone and detoxification protein human Atox1 homologue (HAH), and down regulation of XRCC5 expression using siRNA led to enhanced HAH expression when cells were exposed to Cu. XRCC5 could also be purified from cytosolic extracts using a Cu-loaded column. These findings provide further evidence that cytosolic XRCC5 has a key role in protection against DNA oxidation from Cu, through either direct sequestration or signaling through other Cu-detoxification molecules. Our findings have important implications for the development of therapeutic treatments targeting Cu in neurodegeneration and/or cancer.
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Cobre/metabolismo , Citosol/metabolismo , ADN Helicasas/metabolismo , Antígenos Nucleares/biosíntesis , Muerte Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Cobre/farmacología , Citosol/efectos de los fármacos , Daño del ADN , ADN Helicasas/biosíntesis , Reparación del ADN , Proteínas de Unión al ADN/biosíntesis , Relación Dosis-Respuesta a Droga , Células HeLa , Humanos , Autoantígeno Ku , Estrés Oxidativo/efectos de los fármacosRESUMEN
Brain tumors such as neuroblastomas and gliomas are often refractory to current treatments. Development of metal-based drugs may offer an alternative approach due to the ability to deliver radionuclides or cytotoxic metals to the tumor. Previous studies have shown that diacetyl-bis(N(4)-methylthiosemicarbazonato)-copper(II) (Cu(II)(atsm)) can selectively target hypoxic tumors and this feature has been utilized for development of imaging and radiotherapy. However, we have recently shown that glyoxal-bis(N(4)-methylthiosemicarbazonato)-copper(II) (Cu(II)(gtsm)) can target the brain in animal models of neurodegeneration. Unlike Cu(II)(atsm), Cu(II)(gtsm) is able to release Cu intracellularly under normoxic conditions. Glyoxal-bis(thiosemicarbazones) have reported anticancer effects but little is known about the cellular mechanisms involved. Therefore, in this study, we used protein microarray analysis to investigate the effect of Cu(II)(gtsm) on neuroblastoma cell growth in vitro. Treatment of the human neuroblastoma cell line BE(2)-M17, resulted in cell cycle arrest as assessed by fluorescent activated cell sorting (FACS) analysis. Rapidly arrested growth was not associated with onset of apoptosis. Instead, protein microarray analysis revealed that Cu(II)(gtsm) rapidly and potently reduced cyclin D1 expression, while increasing Kip2 expression. Other changes observed were decreased Cdk7 expression and activation of CHK2. These changes may be associated with the cell cycle arrest. We also observed a potent decrease of total and phosphorylated insulin-like growth factor receptor (IGF-IR) by Cu(II)(gtsm) which is associated with modulation of cyclin D1 expression. Our studies reveal important insights into the potential anticancer activity of Cu(II)(gtsm). Further studies are needed to examine the therapeutic potential of Cu(II)(gtsm) and other bis(thiosemicarbazonato) metal complexes as metallo-drugs for treatment of systemic or brain tumors.
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Antineoplásicos/farmacología , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/patología , Cobre/química , Neuroblastoma/tratamiento farmacológico , Neuroblastoma/patología , Compuestos Organometálicos/farmacología , Tiosemicarbazonas/química , Antineoplásicos/síntesis química , Antineoplásicos/química , Ciclo Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Ensayos de Selección de Medicamentos Antitumorales , Citometría de Flujo , Humanos , Estructura Molecular , Compuestos Organometálicos/síntesis química , Compuestos Organometálicos/química , Estereoisomerismo , Células Tumorales CultivadasRESUMEN
Quinidine derivative (QD)(2)PYR was found to catalyze the asymmetric direct amination of unprotected prochiral 3-oxindole with DIAD to construct quaternary stereocenters at the C3 position with excellent enantioselectivity.
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Aminas/química , Indoles/química , Aminación , Catálisis , Oxindoles , EstereoisomerismoRESUMEN
Accumulation of neurotoxic amyloid-beta (Abeta) is central to the pathology of Alzheimer's disease (AD). Elucidating the mechanisms of Abeta accumulation will therefore expedite the development of Abeta-targeting AD therapeutics. We examined activity of an Abeta-degrading protease (matrix metalloprotease 2) to investigate whether biochemical factors consistent with conditions in the AD brain contribute to Abeta accumulation by altering Abeta sensitivity to proteolytic degradation. An Abeta amino acid mutation found in familial AD, Abeta interactions with zinc (Zn), and increased Abeta hydrophobicity all strongly prevented Abeta degradation. Consistent to all of these factors is the promotion of specific Abeta aggregates where the protease cleavage site, confirmed by mass spectrometry, is inaccessible within an amyloid structure. These data indicate decreased degradation due to amyloid formation initiates Abeta accumulation by preventing normal protease activity. Zn also prevented Abeta degradation by the proteases neprilysin and insulin degrading enzyme. Treating Zn-induced Abeta amyloid with the metal-protein attenuating compound clioquinol reversed amyloid formation and restored the peptide's sensitivity to degradation by matrix metalloprotease 2. This provides new data indicating that therapeutic compounds designed to modulate Abeta-metal interactions can inhibit Abeta accumulation by restoring the catalytic potential of Abeta-degrading proteases.
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Péptidos beta-Amiloides/metabolismo , Amiloide/metabolismo , Amiloide/efectos de los fármacos , Péptidos beta-Amiloides/efectos de los fármacos , Péptidos beta-Amiloides/genética , Clioquinol/farmacología , Relación Dosis-Respuesta a Droga , Ensayo de Inmunoadsorción Enzimática/métodos , Ácido Glutámico/genética , Glutamina/genética , Humanos , Insulisina/farmacología , Metaloproteinasa 2 de la Matriz/metabolismo , Microscopía Electrónica de Transmisión/métodos , Mutación , Neprilisina/farmacología , Fragmentos de Péptidos/efectos de los fármacos , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Factores de Tiempo , Zinc/farmacologíaRESUMEN
Cognitive decline in Alzheimer's disease (AD) involves pathological accumulation of synaptotoxic amyloid-beta (Abeta) oligomers and hyperphosphorylated tau. Because recent evidence indicates that glycogen synthase kinase 3beta (GSK3beta) activity regulates these neurotoxic pathways, we developed an AD therapeutic strategy to target GSK3beta. The strategy involves the use of copper-bis(thiosemicarbazonoto) complexes to increase intracellular copper bioavailability and inhibit GSK3beta through activation of an Akt signaling pathway. Our lead compound Cu(II)(gtsm) significantly inhibited GSK3beta in the brains of APP/PS1 transgenic AD model mice. Cu(II)(gtsm) also decreased the abundance of Abeta trimers and phosphorylated tau, and restored performance of AD mice in the Y-maze test to levels expected for cognitively normal animals. Improvement in the Y-maze correlated directly with decreased Abeta trimer levels. This study demonstrates that increasing intracellular copper bioavailability can restore cognitive function by inhibiting the accumulation of neurotoxic Abeta trimers and phosphorylated tau.
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Péptidos beta-Amiloides/efectos de los fármacos , Cobre/farmacología , Proteínas tau/efectos de los fármacos , Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/metabolismo , Animales , Encéfalo/metabolismo , Cognición/efectos de los fármacos , Cobre/farmacocinética , Cobre/uso terapéutico , Dimerización , Modelos Animales de Enfermedad , Glucógeno Sintasa Quinasa 3/antagonistas & inhibidores , Glucógeno Sintasa Quinasa 3 beta , Glucógeno Sintasa Quinasas/antagonistas & inhibidores , Aprendizaje por Laberinto , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Compuestos Organometálicos/farmacocinética , Fosforilación/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas tau/metabolismoRESUMEN
OBJECTIVE: To explore the satisfactory rate in patients with body dysmorphic disorder (BDD) after cosmetic surgery. METHODS: We designed a questionnaire to investigate the postoperative satisfactory rate in patients with BDD and without BDD. RESULTS: There was significant difference in postoperative satisfactory rate between patients with BDD and without BDD. CONCLUSION: The patients with BDD have a lower satisfactory rate, which is even worse after repeated surgery.
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Trastorno Dismórfico Corporal/psicología , Satisfacción del Paciente , Cirugía Plástica , Adulto , Imagen Corporal , Femenino , Humanos , Masculino , Persona de Mediana Edad , Encuestas y CuestionariosRESUMEN
This paper studied the stem sap flow of grape in arid oasis region of Shiyang River basin under conventional drip irrigation (CDI), alternate drip irrigation (ADI), and fixed drip irrigation (FDI), and its relationships with meteorological conditions and soil moisture content. The results showed that the stem sap flow of grape had an obvious day-night rhythm synchronous with solar radiation, and was significantly higher under CDI than under ADI and FDI during new branch growth and flowering stages. Solar radiation and air temperature were the main meteorological factors affecting the hourly sap flow, and the daily stem sap flow had linear relationships with daily air temperature and wind speed. The correlation coefficients between the stem sap flow and the meteorological factors ranked in the order of CDI > ADI > FDI. There was a significant correlation between daily stem sap flow and reference crop evapotranspiration (ET0). Compared with CDI, ADI could save 50% of irrigation water while the stem sap flow only reduced by 6.56%, and an obvious compensation effect between stem sap flow and hydraulic conductivity was observed.
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Clima Desértico , Tallos de la Planta/metabolismo , Vitis/metabolismo , Agua/metabolismo , Agricultura/métodos , China , Ambiente , Transpiración de Plantas , Ríos , Movimientos del AguaRESUMEN
Neurodegenerative illnesses are characterized by aberrant metabolism of biometals such as copper (Cu), zinc (Zn) and iron (Fe). However, little is known about the metabolic effects associated with altered metal homeostasis. In this study, we used an in vitro model of altered Cu homeostasis to investigate how Cu regulates cellular protein expression. Human fibroblasts containing a natural deletion mutation of the Menkes (MNK) ATP7A Cu transporter (MNK deleted) were compared to fibroblasts overexpressing ATP7A (MNK transfected). Cultures of MNK-transfected (Low-Cu) cells exhibited 95% less intracellular Cu than MNK-deleted (High-Cu) cells. Comparative proteomic analysis of the two cell-lines was performed using antibody microarrays, and significant differential protein expression was observed between Low-Cu and High-Cu cell-lines. Western blot analysis confirmed the altered protein expression of Ku80, nexilin, L-caldesmon, MAP4, Inhibitor 2 and DNA topoisomerase I. The top 50 altered proteins were analysed using the software program Pathway Studio (Ariadne Genomics) and revealed a significant over-representation of proteins involved in DNA repair and maintenance. Further analysis confirmed that expression of the DNA repair protein Ku80 was dependent on cellular Cu homeostasis and that Low-Cu levels in fibroblasts resulted in elevated susceptibility to DNA oxidation.
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Adenosina Trifosfatasas/genética , Proteínas de Transporte de Catión/genética , Cobre/química , Fibroblastos/metabolismo , Adenosina Trifosfatasas/química , Adenosina Trifosfatasas/metabolismo , Antígenos Nucleares/biosíntesis , Transporte Biológico , Proteínas de Transporte de Catión/química , Proteínas de Transporte de Catión/metabolismo , Biología Computacional/métodos , ATPasas Transportadoras de Cobre , ADN/química , Proteínas de Unión al ADN/biosíntesis , Humanos , Autoantígeno Ku , Enfermedades Neurodegenerativas/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Oxígeno/química , Análisis por Matrices de Proteínas , Proteómica/métodos , Programas InformáticosRESUMEN
The epidermal growth factor receptor is a receptor tyrosine kinase expressed in a range of tissues and cell-types. Activation of the epidermal growth factor receptor by a number of ligands induces downstream signalling that modulates critical cell functions including growth, survival and differentiation. Abnormal epidermal growth factor receptor expression and activation is also involved in a number of cancers. In addition to its cognate ligands, the epidermal growth factor receptor can be activated by metals such as zinc (Zn) and copper (Cu). Due to the important role of these metals in a number of diseases including neurodegenerative disorders, therapeutic approaches are being developed based on the use of lipid permeable metal-complexing molecules. While these agents are showing promising results in animal models and clinical trials, little is known about the effects of metal-ligand complexes on cell signalling pathways. In this study, we investigated the effects of clioquinol (CQ)-metal complexes on activation of epidermal growth factor receptor. We show here that CQ-Cu complexes induced potent epidermal growth factor receptor phosphorylation resulting in downstream activation of extracellular signal-regulated kinase. Similar levels of epidermal growth factor receptor activation were observed with alternative lipid permeable metal-ligands including neocuproine and pyrrolidine dithiocarbamate. We found that CQ-Cu complexes induced a significant reduction in the level of extracellular Abeta1-40 in cell culture. Inhibition of epidermal growth factor receptor activation by PD153035 blocked extracellular signal-regulated kinase phosphorylation and restored Abeta1-40 levels. Activation of the epidermal growth factor receptor by CQ-Cu was mediated through up-regulation of src kinase activity by a cognate ligand-independent process involving membrane integrins. These findings provide the first evidence that metal-ligand complexes can activate the epidermal growth factor receptor with potentially neuroprotective effects.
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Péptidos beta-Amiloides/metabolismo , Cobre/metabolismo , Receptores ErbB/metabolismo , Espacio Extracelular/efectos de los fármacos , Espacio Extracelular/metabolismo , Compuestos Organometálicos/farmacología , Animales , Línea Celular , Clioquinol/metabolismo , Cobre/farmacología , Cricetinae , Activación Enzimática , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Receptores ErbB/agonistas , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Humanos , Integrinas/metabolismo , Ligandos , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Compuestos Organometálicos/metabolismo , Fosforilación/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacos , Familia-src Quinasas/metabolismoRESUMEN
Biometals such as copper and zinc have an important role in Alzheimer's disease (AD). Accumulating evidence indicates that copper homeostasis is altered in AD brain with elevated extracellular and low intracellular copper levels. Studies in animals and cell cultures have suggested that increasing intracellular copper can ameliorate AD-like pathology including amyloid deposition and tau phosphorylation. Modulating copper homeostasis can also improve cognitive function in animal models of AD. Treatments are now being developed that may result in redistribution of copper within the brain. Metal ligands such as clioquinol (CQ), DP-109 or pyrrolidine dithiocarbamate (PDTC) have shown promising results in animal models of AD, however, the actual mode of action in vivo has not been fully determined. We previously reported that CQ-metal complexes were able to increase intracellular copper levels in vitro. This resulted in stimulation of phosphoinositol-3-kinase activity and mitogen activated protein kinases (MAPK). Increased kinase activity resulted in up-regulated matrix metalloprotease (MMP2 and MMP3) activity resulting in enhanced degradation of secreted A beta. These findings are consistent with previous studies reporting metal-mediated activation of MAPKs and MMPs. How this activation occurs is unknown but evidence suggests that copper may be able to activate membrane receptors such as the epidermal growth factor receptor (EGFR) and result in downstream activation of MAPK pathways. This has been supported by studies showing metal-mediated activation of EGFR through ligand-independent processes in a number of cell-types. Our initial studies reveal that copper complexes can in fact activate EGFR. However, further studies are necessary to determine if metal complexes such as CQ-copper induce up-regulation of A beta-degrading MMP activity through this mechanism. Elucidation of this pathway may have important implications for the development of metal ligand based therapeutics for treatment of AD and other neurodegenerative disorders.
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Enfermedad de Alzheimer/fisiopatología , Encéfalo/efectos de los fármacos , Encéfalo/fisiopatología , Quelantes/farmacología , Cobre , Metaloproteinasas de la Matriz Secretadas/metabolismo , Amiloide/efectos de los fármacos , Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Animales , Encéfalo/enzimología , Técnicas de Cultivo de Célula , Quelantes/uso terapéutico , Clioquinol/uso terapéutico , Cobre/química , Cobre/metabolismo , Cobre/farmacología , Modelos Animales de Enfermedad , Ácido Egtácico/análogos & derivados , Ácido Egtácico/uso terapéutico , Activación Enzimática/efectos de los fármacos , Receptores ErbB/efectos de los fármacos , Receptores ErbB/metabolismo , Humanos , Espacio Intracelular/metabolismo , Proteínas Quinasas Activadas por Mitógenos/efectos de los fármacos , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Placa Amiloide/efectos de los fármacos , Prolina/análogos & derivados , Prolina/uso terapéutico , Tiocarbamatos/uso terapéutico , Oligoelementos/metabolismo , Zinc/metabolismoRESUMEN
Copper and zinc play important roles in Alzheimer disease pathology with recent reports describing potential therapeutics based on modulation of metal bioavailability. We examined the ability of a range of metal bis(thiosemicarbazonato) complexes (MII(btsc), where M=CuII or ZnII) to increase intracellular metal levels in Chinese hamster ovary cells overexpressing amyloid precursor protein (APP-CHO) and the subsequent effect on extracellular levels of amyloid-beta peptide (Abeta). The CuII(btsc) complexes were engineered to be either stable to both a change in oxidation state and dissociation of metal or susceptible to intracellular reduction and dissociation of metal. Treatment of APP-CHO cells with stable complexes resulted in elevated levels of intracellular copper with no effect on the detected levels of Abeta. Treatment with complexes susceptible to intracellular reduction increased intracellular copper levels but also resulted in a dose-dependent reduction in the levels of monomeric Abeta. Treatment with less stable ZnII(btsc) complexes increased intracellular zinc levels with a subsequent dose-dependent depletion of monomeric Abeta levels. The increased levels of intracellular bioavailable copper and zinc initiated a signaling cascade involving activation of phosphoinositol 3-kinase and c-Jun N-terminal kinase. Inhibition of these enzymes prevented Abeta depletion induced by the MII(btsc) complexes. Inhibition of metalloproteases also partially restored Abeta levels, implicating metal-driven metalloprotease activation in the extracellular monomeric Abeta depletion. However, a role for alternative metal-induced Abeta metabolism has not been ruled out. These studies demonstrate that MII(btsc) complexes have potential for Alzheimer disease therapy.
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Enfermedad de Alzheimer/tratamiento farmacológico , Precursor de Proteína beta-Amiloide/metabolismo , Cobre/farmacología , Tiosemicarbazonas/farmacología , Zinc/farmacología , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animales , Disponibilidad Biológica , Células CHO , Cobre/farmacocinética , Cobre/uso terapéutico , Cricetinae , Cricetulus , Relación Dosis-Respuesta a Droga , Evaluación Preclínica de Medicamentos , Expresión Génica , Humanos , Oxidación-Reducción/efectos de los fármacos , Tiosemicarbazonas/farmacocinética , Tiosemicarbazonas/uso terapéutico , Zinc/química , Zinc/farmacocinética , Zinc/uso terapéuticoRESUMEN
Loss of intracellular neuronal glutathione (GSH) is an important feature of neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. The consequences of GSH depletion include increased oxidative damage to proteins, lipids, and DNA and subsequent cytotoxic effects. GSH is also an important modulator of cellular copper (Cu) homeostasis and altered Cu metabolism is central to the pathology of several neurodegenerative diseases. The cytotoxic effects of Cu in cells depleted of GSH are not well understood. We have previously reported that depletion of neuronal GSH levels results in cell death from trace levels of extracellular Cu due to elevated Cu(I)-mediated free radical production. In this study we further examined the molecular pathway of trace Cu toxicity in neurons and fibroblasts depleted of GSH. Treatment of primary cortical neurons or 3T3 fibroblasts with the glutathione synthetase inhibitor buthionine sulfoximine resulted in substantial loss of intracellular GSH and increased cytotoxicity. We found that both neurons and fibroblasts revealed increased expression and activation of p53 after depletion of GSH. The increased p53 activity was induced by extracellular trace Cu. Furthermore, we showed that in GSH-depleted cells, Cu induced an increase in oxidative stress resulting in DNA damage and activation of p53-dependent cell death. These findings may have important implications for neurodegenerative disorders that involve GSH depletion and aberrant Cu metabolism.
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Cobre/metabolismo , Glutatión , Proteína p53 Supresora de Tumor/metabolismo , Células 3T3 , Animales , Butionina Sulfoximina/farmacología , Muerte Celular/fisiología , Corteza Cerebral/citología , Daño del ADN , Inhibidores Enzimáticos/farmacología , Radicales Libres/metabolismo , Regulación de la Expresión Génica , Glutatión/deficiencia , Glutatión Sintasa/antagonistas & inhibidores , Ratones , Enfermedades Neurodegenerativas/etiología , Enfermedades Neurodegenerativas/metabolismo , Neuronas/citología , Neuronas/metabolismo , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Copper has an important role in cancer growth, angiogenesis, and metastasis. Previous studies have shown that cell-permeable metal ligands, including clioquinol (CQ) and pyrrolidine dithiocarbamate, inhibit cancer cell growth in cell culture and in vivo. The mechanism of action has not been fully determined but may involve metal-mediated inhibition of cancer cell proteasome activity. However, these studies do not fully account for the ability of cell-permeable metal ligands to inhibit cancer cell growth without affecting normal cells. In this study, we examined the effect of CQ on macrophage-mediated inhibition of HeLa cancer cell growth in vitro. When CQ was added to RAW 264.7 macrophage-HeLa cell cocultures, a substantial increase in HeLa cell toxicity was observed compared with CQ treatment of HeLa cells cultured alone. Transfer of conditioned medium from CQ-treated macrophages to HeLa cells also induced HeLa cell toxicity, demonstrating the role of secreted factors in the macrophage-mediated effect. Further investigation revealed that CQ induced copper-dependent activation of macrophages and release of tumor necrosis factor (TNF) alpha. In studies with recombinant TNFalpha, we showed that the level of TNFalpha released by CQ-treated macrophages was sufficient to induce HeLa cell toxicity. Moreover, the toxic effect of conditioned medium from CQ-treated macrophages could be prevented by addition of neutralizing antibodies to TNFalpha. These studies demonstrate that CQ can induce cancer cell toxicity through metal-dependent release of TNFalpha from macrophages. Our results may help to explain the targeted inhibition of tumor growth in vivo by CQ.
Asunto(s)
Antineoplásicos/farmacología , Clioquinol/farmacología , Macrófagos/efectos de los fármacos , Factor de Necrosis Tumoral alfa/metabolismo , Animales , Línea Celular , Supervivencia Celular/efectos de los fármacos , Cobre/farmacología , Citocinas/metabolismo , Células HeLa , Humanos , Macrófagos/metabolismo , Ratones , Proteínas Recombinantes/farmacología , Factor de Necrosis Tumoral alfa/farmacologíaRESUMEN
A growing body of evidence supports a central role for biometals in neurodegenerative disorders. Biometals induce oxidative stress through the generation of reactive oxygen species and contribute to neuronal cell dysfunction in Alzheimer's disease (AD), prion disorders and Parkinson's disease (PD). Therapies based on modulation of biometal metabolism are currently being developed and the metal ligand, 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol or CQ) has been investigated for the treatment of AD. CQ has also shown therapeutic benefits in an animal model of PD. However, little is known about the neuroprotective processes of CQ in vivo. In this study, we examined the effect of CQ in BE(2)-M17 human neuroblastoma cells exposed to increased oxidative stress (hydrogen peroxide (H2O2) treatment). Although CQ alone induced a moderate toxic effect on cells, when added to H2O2-treated M17 cells, CQ induced a significant inhibition of H2O2 toxicity. This correlated with up-regulation of phosphoinositol-3-kinase (PI3K) activity in CQ-treated cells. The protective action of CQ was not observed in murine N2a neuroblastoma cells treated with H2O2 and this cell-line did not reveal CQ-mediated increases in PI3K activation. The protective effect was specific for CQ and was not induced by a number of different metal ligands. Inhibition of PI3K activity with LY294002 prevented CQ protection against H2O2 toxicity, demonstrating a crucial role for CQ activation of PI3K in protection against oxidative stress. Furthermore, CQ inhibited H2O2-mediated up-regulation of p53 activity in the M17 cells and this was dependent on PI3K activation. Our studies demonstrate that in human M17 cells, CQ can protect against oxidative stress by activating the PI3K-dependent survival pathway and blocking p53-mediated cell death. These findings have important implications for the development of protective metal ligand-based therapies for treatment of disorders involving oxidative stress.
Asunto(s)
Clioquinol/farmacología , Peróxido de Hidrógeno/antagonistas & inhibidores , Fármacos Neuroprotectores/farmacología , Estrés Oxidativo/efectos de los fármacos , Fosfatidilinositol 3-Quinasas/metabolismo , Proteína p53 Supresora de Tumor/antagonistas & inhibidores , Animales , Línea Celular Tumoral , Humanos , Peróxido de Hidrógeno/toxicidad , Ratones , Regulación hacia ArribaRESUMEN
By using heat pulse technique, an investigation on the transpiration of Hedysarum scoparium was conducted in the arid desert region of Shiyang River basin, Gansu Province. The results indicated that with increasing inserted depth of probe, the sap flow velocity in H. scoparium xylem had a trend from high to low. In the taproot with smaller diameter, the average sap flow velocity at different positions was faster, and the change range was bigger. Among the taproots with different diameters, there existed a larger difference in the magnitude of sap flux, but the change trend was similar, i. e., smaller at nighttime and larger at daytime, and showing a multi-peak curve. A linear correlation was observed between the diurnal sap flux and the reference crop evapotranspiration, and the transpiration mainly occurred during the period from June to September, occupying 79.04% of the total annual transpiration. The diurnal sap flux of H. scoparium at its later growth period had significant correlation with the moisture content in 0-50 cm sand layer, but no correlations with that in other sand layers. The effects of main meteorological factors on the sap flux of H. scoparium were in the sequence of air temperature > vapor pressure difference > wind speed.
Asunto(s)
Clima Desértico , Fabaceae/fisiología , Transpiración de Plantas/fisiología , China , RíosRESUMEN
Biometals have an important role in AD (Alzheimer's disease) and metal ligands have been investigated as potential therapeutic agents for treatment of AD. In recent studies the 8HQ (8-hydroxyquinoline) derivative CQ (clioquinol) has shown promising results in animal models and small clinical trials; however, the actual mode of action in vivo is still being investigated. We previously reported that CQ-metal complexes up-regulated MMP (matrix metalloprotease) activity in vitro by activating PI3K (phosphoinositide 3-kinase) and JNK (c-jun N-terminal kinase), and that the increased MMP activity resulted in enhanced degradation of secreted Abeta (amyloid beta) peptide. In the present study, we have further investigated the biochemical mechanisms by which metal ligands affect Abeta metabolism. To achieve this, we measured the effects of diverse metal ligands on cellular metal uptake and secreted Abeta levels in cell culture. We report that different classes of metal ligands including 8HQ and phenanthroline derivatives and the sulfur compound PDTC (pyrrolidine dithiocarbamate) elevated cellular metal levels (copper and zinc), and resulted in substantial loss of secreted Abeta. Generally, the ability to inhibit Abeta levels correlated with a higher lipid solubility of the ligands and their capacity to increase metal uptake. However, we also identified several ligands that potently inhibited Abeta levels while only inducing minimal change to cellular metal levels. Metal ligands that inhibited Abeta levels [e.g. CQ, 8HQ, NC (neocuproine), 1,10-phenanthroline and PDTC] induced metal-dependent activation of PI3K and JNK, resulting in JNK-mediated up-regulation of metalloprotease activity and subsequent loss of secreted Abeta. The findings in the present study show that diverse metal ligands with high lipid solubility can elevate cellular metal levels resulting in metalloprotease-dependent inhibition of Abeta. Given that a structurally diverse array of ligands was assessed, the results are consistent with the effects being due to metal transport rather than the chelating ligand interacting directly with a receptor.