62 research outputs found
Impact of the new definition for pulmonary hypertension in patients with lung disease: an analysis of the United Network for Organ Sharing database
The implications of the recent change in the definition of pulmonary hypertension on epidemiology and outcomes are not known. We sought to determine the percentage of patients with the two most common lung diseases that would be reclassified regarding the presence/absence of pulmonary hypertension with the revised definition. A query of the United Network for Organ Sharing database was performed. The percentage of patients meeting the current and previous definition of pulmonary hypertension was described. Outcomes of patients stratified by the current and previous definitions were compared. There were 15,563 patients with right heart catheterization data analyzed. Pulmonary hypertension was more prevalent in both chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis under the new definition at 52.4% versus 82.4%, and 47.6% versus 73.6%, respectively. 'Pre-capillary' pulmonary hypertension by the new definition was lower at 28.1% for chronic obstructive pulmonary disease and 36.8% for idiopathic pulmonary fibrosis. Of the patients with pulmonary hypertension by the old definition, 23.9% of chronic obstructive pulmonary disease patients and 18.7% of idiopathic pulmonary fibrosis patients were not classified as pulmonary hypertension by the new definition. Conversely, 15.9% of chronic obstructive pulmonary disease patients and 15.1% of idiopathic pulmonary fibrosis patients who did not meet diagnostic criteria for pulmonary hypertension by the old definition did have pulmonary hypertension by the new definition. Patients in both disease categories had shorter transplant-free waitlist survival in the presence of pulmonary hypertension by both the new and old definitions. There was a trend toward the new definition of pre-capillary pulmonary hypertension better discerning outcomes compared to the old definition of pulmonary hypertension in idiopathic pulmonary fibrosis patients. Most patients with advanced lung disease who are listed for lung transplantation have pulmonary hypertension, but fewer have pre-capillary pulmonary hypertension than pulmonary hypertension by the old definition. Both the old and new definition of precapillary pulmonary hypertension appear to discern outcomes among the two groups of lung disease analyzed, with some evidence to suggest that the new definition performs slightly better in the idiopathic pulmonary fibrosis population
Optimisation and investment analysis of two biomass-to-heat supply chain structures
As oil prices have risen dramatically lately, many people explore alternative ways of heating their residences and businesses in order to reduce the respective cost. One of the options usually considered nowadays is biomass, especially in rural areas with significant local biomass availability. This work focuses on comparing two different biomass energy exploitation systems, aiming to provide heat to a specific number of customers at a specific cost. The first system explored is producing pellets from biomass and distributing them to the final customers for use in domestic pellet boilers. The second option is building a centralised co-generation (CHP) unit that will generate electricity and heat. Electricity will be fed to the grid, whereas heat will be distributed to the customers via a district heating network. The biomass source examined is agricultural residues and the model is applied to a case study region in Greece. The analysis is performed from the viewpoint of the potential investor. Several design characteristics of both systems are optimised. In both cases the whole biomass-to-energy supply chain is modelled, both upstream and downstream of the pelleting/CHP units. The results of the case study show that both options have positive financial yield, with the pelleting plant having higher yield. However, the sensitivity analysis reveals that the pelleting plant yield is much more sensitive than that of the CHP plant, therefore constituting a riskier investment. The model presented may be used as a decision support system for potential investors willing to engage in the biomass energy field
Polyamine Sharing between Tubulin Dimers Favours Microtubule Nucleation and Elongation via Facilitated Diffusion
We suggest for the first time that the action of multivalent cations on
microtubule dynamics can result from facilitated diffusion of GTP-tubulin to the
microtubule ends. Facilitated diffusion can promote microtubule assembly,
because, upon encountering a growing nucleus or the microtubule wall, random
GTP-tubulin sliding on their surfaces will increase the probability of
association to the target sites (nucleation sites or MT ends).
This is an original explanation for understanding the apparent discrepancy
between the high rate of microtubule elongation and the low rate of tubulin
association at the microtubule ends in the viscous cytoplasm. The mechanism of
facilitated diffusion requires an attraction force between two tubulins, which
can result from the sharing of multivalent counterions. Natural polyamines
(putrescine, spermidine, and spermine) are present in all
living cells and are potent agents to trigger tubulin self-attraction. By using
an analytical model, we analyze the implication of facilitated diffusion
mediated by polyamines on nucleation and elongation of microtubules. In
vitro experiments using pure tubulin indicate that the promotion of
microtubule assembly by polyamines is typical of facilitated diffusion. The
results presented here show that polyamines can be of particular importance for
the regulation of the microtubule network in vivo and provide
the basis for further investigations into the effects of facilitated diffusion
on cytoskeleton dynamics
Comportamento fotofÃsico do antraceno em sistemas micro-heterogêneos argila-surfactantes-Ãons metálicos
Argilas constituem uma classe de complexos micro-heterogêneos e podem ser utilizados como substrato para adsorção. O seu comportamento de sorção em fase sólida intensificada pela presença de surfactantes, argilas organofÃlicas, é um importante fenômeno explorado pela tecnologia ambiental para a remoção de compostos orgânicos policÃclicos (hidrocarbonetos aromáticos policÃclicos, HPA) da água, introduzidos no ambiente por fontes antropogênicas. Este trabalho tem por objetivo estudar o comportamento fotofÃsico do antraceno, como modelo de HPA, em sistemas micro-heterogêneos argila-surfactantes-Ãons metálicos (M(II)= Cd(II), Cu(II), Hg(II), Ni(II) e Pb(II); surfactantes: CTACl; SDS; TR-X100). Os estudos foram conduzidos pelo monitoramento na mudança das propriedades de fluorescência estática e na supressão da emissão do antraceno utilizado como sonda fluorescente. Como supressores foram utilizados os cátions metálicos: Cd(II), Cu(II), Hg(II), Ni(II) e Pb(II). O perfil do espectro de fluorescência e os resultados dos ensaios de supressão da fluorescência da sonda permitiram inferir na localização do sÃtio de solubilização do antraceno nos sistemas micro-heterogêneos estudados e na conseqüente organização dos mesmos.Clays are a class of complex micro-heterogeneous and can be used as a substrate for adsorption. The sorption behavior of solid-phase enhanced by the presence of surfactants, organoclay, is an important phenomenon studied by environmental technology for removal of polycyclic aromatic hydrocarbons (PAHs) anthropogenic sources from water. This work aims to study the photophysical behavior of anthracene as a model of HPA systems in micro-heterogeneous clay-surfactant-metal ions (M (II) = Cd (II), Cu (II), Hg (II), Ni (II) and Pb (II); surfactants: CTACl; SDS; TR-X100). The experimental assays were conducted by monitoring changes in the static properties of fluorescence and anthracene emission suppression; anthracene was used as fluorescent probe. M(II)ions, like Cd(II), Cu(II), Hg(II), Ni(II) and Pb(II)were used as anthracene fluorescence suppressors. The profile of the fluorescence spectrum and the results of the suppression of fluorescence of the probe allowed inferring the specific place of the anthracene solubilization into the micro-heterogeneous systems studied and the consequent arrangement of them
Estudo espectro eletroquÃmico de sistemas estruturados argila-corante
O comportamento eletroquÃmico e espectroeletroquÃmico do sistema montmorilonita-azul de metileno (MM-AM)/AMsolução foi investigado empregando-se a técnica de voltametria cÃclica e de transiente, I x t (corrente versus tempo) sobre eletrodo de vidro ITO modificado pela deposição mecânica de filmes do compósito MM-AM. Os filmes foram preparados empregando três procedimentos: 1- na ausência de CTACl (surfactante, cloreto de cetiltrimetilamônio); 2- com incorporação do CTACl à região interlamelar; e 3- na presença do CTACl, porém, não incorporado à região interlamelar. A técnica espectrofotométrica foi empregada para a caracterização e para o estudo eletrocrômico dos filmes formados. Os resultados experimentais permitiram observar que: i- os filmes preparados com a incorporação prévia do AM a região interlamelar fornecem uma resposta eletroquÃmica mais eficiente com o aparecimento de um par de picos bem definido; ii- a adição do CTACl, de forma geral permite a obtenção de filmes mecanicamente mais estáveis; iii- com a inclusão prévia do CTACl na região interlamelar não ocorre o aparecimento da forma protonada do AM (AMH+); iv- na ausência da forma protonada o compósito não apresenta comportamento eletrocrômico.The eletrochemical and espectroelectrochemical behavior of the montmorilonita methylene-blue system (MM-AM)/AMsolution have been investigated using cyclic volta mmetry and transient (I x t) techniques on modified ITO glass electrodes by film of composite (MM-AM) mechanically deposited. These films were prepared by three way: 1- in the absence of surfactant CTACl (cetyltrimethyl-ammonuim chloride); 2- with incorporation of CTACl into the interlayer region; and 3- in the presence of CTACl, however, not incorporated into the interlayer region. The spectroelectrochemistry technique was used for characterization and study of the formed films. The experimental results allowed assumptions as follows: 1- films prepared with AM previous incorporated into interlayer region supply a more efficient electrochemistry answer with the appearance of a couple of well defined peaks; 2- CTACl, in general, allows to obtain mechanically stable films; 3- when CTACl is previously included into interlayer region it doesn't exist intercalated protonated specie, AMH+; 4- when protonated specie is absent the composite doesn't shows electrochromic behavior.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP
Thermal behaviour of intercalated 8-hydroxyquinoline (oxine) in montmorillonite clay
The composite montmorillonite-8-hydroxyquinoline (Swy-1-8-HQ) was prepared by two different processes and studied by using thermogravimetric analysis (TG/DTG and DSC), as well as helpful techniques as fluorescence in the UV-visible region and X-ray diffraction. The composites developed fluorescent appearance, however with quantum poor efficiency and they exhibited distinct TG and DSC thermal behavior. The fluorescence data of spectra associated to the TG/DT curves allowed to suggest that the 8-HQ was present in the composites in two different circumstances: 1 - intercalated in the interlayer spaces (Swy-1-8-HQ2), rigidly associated to the Substrate feasible as a monolayer with the aromatic rings parallel to the silica layer; and/or, 2 - adsorbed on the Surface (Swy-1-8-HQ1), either as a bilayer formation or tilting of the molecules to the silicate layer sheet. All results confirmed above are in agreement with X-ray diffraction patterns, once the interlayer space increases when 8-HQ is incorporated. The experimental results confirm the formation of the composites in agreement with the method used in the preparation
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