The antioxidant effect of caffeine, associated with its ability to upregulate the nuclear factor-E2-related factor-2 (Nrf2)-signaling pathway, was explored as a possible mechanism for the attenuation ...of liver damage. Nonalcoholic steatohepatitis (NASH) was induced in rats by the administration of a high-fat, high-sucrose, high-cholesterol diet (HFSCD) for 15 weeks. Liver damage was induced in rats by intraperitoneal administration of thioacetamide (TAA) for six weeks. Caffeine was administered orally at a daily dose of 50 mg/kg body weight during the period of NASH induction to evaluate its ability to prevent disease development. Meanwhile, rats received TAA for three weeks, after which 50 mg/kg caffeine was administered daily for three weeks with TAA to evaluate its capacity to interfere with the progression of hepatic injury. HFSCD administration induced hepatic steatosis, decreased Nrf2 levels, increased oxidative stress, induced the activation of nuclear factor-κB (NF-κB), and elevated proinflammatory cytokine levels, leading to hepatic damage. TAA administration produced similar effects, excluding steatosis. Caffeine increased Nrf2 levels; attenuated oxidative stress markers, including malondialdehyde and 4-hydroxynonenal; restored normal, reduced glutathione levels; and reduced NF-κB activation, inflammatory cytokine levels, and damage. Our findings suggest that caffeine may be useful in the treatment of human liver diseases.
Several studies recommend not initiating advanced life support in traumatic cardiac arrest (TCA), mainly owing to the poor prognosis in several series that have been published. This study aimed to ...analyze the survival of the TCA in our series and to determine which factors are more frequently associated with recovery of spontaneous circulation (ROSC) and complete neurologic recovery (CNR).
This is a cohort study (2006-2009) of treatment benefits.
A total of 167 TCAs were analyzed. ROSC was obtained in 49.1%, and 6.6% achieved a CNR. Survival rate by age groups was 23.1% in children, 5.7% in adults, and 3.7% in the elderly (p < 0.05). There was no significant difference in ROSC according to which type of ambulance arrived first, but if the advanced ambulance first, 9.41% achieved a CNR, whereas only 3.7% if the basic ambulance first. We found significant differences between the response time and survival with a CNR (response time was 6.9 minutes for those who achieved a CNR and 9.2 minutes for those who died). Of the patients, 67.5% were in asystole, 25.9% in pulseless electrical activity (PEA), and 6.6% in VF. ROSC was achieved in 90.9% of VFs, 60.5% of PEAs, and 40.2% of those in asystole (p < 0.05), and CNR was achieved in 36.4% of VFs, 7% of PEAs, and 2.7% of those in asystole (p < 0.05). The mean (SD) quantity of fluid replacement was greater in ROSC (1,188.8 786.7 mL of crystalloids and 487.7 688.9 mL of colloids) than in those without ROSC (890.4 622.4 mL of crystalloids and 184.2 359.3 mL of colloids) (p < 0.05).
In our series, 6.6% of the patients survived with a CNR. Our data allow us to state beyond any doubt that advanced life support should be initiated in TCA patients regardless of the initial rhythm, especially in children and those with VF or PEA as the initial rhythm and that a rapid response time and aggressive fluid replacement are the keys to the survival of these patients.
Therapeutic study, level IV; epidemiologic study, level III.
Display omitted
► Pt and Pd-nanoparticles supported on well structured solid acids were applied in catalytic reductive aminations. ► Highly efficient Pt/Al-Beta catalysts could be prepared by ...optimizing Pt and Al contents in solids. ► Pd/MCM-41 catalysts also showed good activities in selective reductive aminations. ► The behaviour of Pt/ and Pd/Al
2O
3 samples strongly depends on the type of alumina pre-treatment used.
Metal catalysts based on Pt and Pd nano-particles supported on structured microporous Beta zeolites and mesoporous MCM-41 materials, as well as specially designed γ-Al
2O
3 samples, were synthesized following a simple and economic procedure. Physico-chemical characterization of metal-composites (by XRD, IR spectroscopy, TEM, N
2 adsorption, ICP, among others) indicated that both Pt and Pd nano-particles were adequately supported and homogeneously dispersed on supports. These metal/solid acid composites were applied as efficient catalysts under mild reaction conditions in the selective reductive amination of ketones, a useful industrial reaction for the synthesis of substituted amines and N-heterocycles. Results obtained showed that Pt/Al-Beta catalyst possesses the best catalytic activity (TON
=
1610, with amine selectivities >95%) superior to that observed with commercial Pt/C and Pt/Al
2O
3 (TON
≈
1000). Enhancements in Pt/Al-Beta samples were achieved by optimizing the Pt loading, and mainly the Si/Al molar ratio in solids. On the contrary, inferior catalytic activities were encountered with the Pt/Si-MCM-41 and Pt/Al-MCM-41 materials. The Pd incorporation on MCM-41 materials produced more active catalysts than the commercial Pd/C and Pd/Al
2O
3 samples. Finally, the study of Pt/ and Pd/γ-Al
2O
3 materials demonstrated that the treatments of support prior to the metal impregnation and the posterior calcinations processes were essentials to obtain efficient catalysts.
Substituted amines and N-heterocycles, useful intermediates in industry, can be synthesized by reductive amination of ketones with amines in the presence of metal supported catalysts. In this work, ...multi-functional catalysts based on Pt, Pd, and Au nanoparticles supported on different metal oxides capable to efficiently catalyze the liquid phase selective reductive amination of ketones have been developed. Catalytic screening performed by HT experimentation showed that Pt-catalysts are more active than the corresponding Pd counterparts, while Au-based materials present very low activities. Excellent results were obtained with Pt/TiO
2 (52% of amine conversion with selectivity >95%, TON
=
2033) followed by Pt/MgO, Pt/CaO, and also Pt/Al
2O
3. Increase in the reduction temperature pre-treatment of Pt-catalysts improved the catalytic activities (≈65% of amine conversion with selectivity >95%, TON
=
2541 for Pt/TiO
2), these values being quite superior to those observed with Pt/C and Pt/Al
2O
3 commercial catalysts. With the appropriate treatment of support prior to metal impregnation efficient Pt/Al
2O
3 materials can also be obtained (TON
=
1685). The results suggest that Pt and Pd catalysts activities can be enhanced by appropriate tailoring the physical and chemical properties of oxide supports depending on the type of metal, this favouring a strong metal-support interaction (SMSI) on solids.
Abstract
Stem development in palms usually involves the building up of a trunk of maximum diameter before emerging from the ground. Unlike most arboreal palms, the oligarchic palm Iriartea deltoidea ...has been shown to grow in both height and diameter. Nevertheless, the drivers of this unusual growth strategy are poorly known. We examined the growth rates of 554 stems found in 10 ha of the 50-ha Yasuní Forest Dynamics Plot. We explored whether palm growth responds to: (1) the size of individual palms; (2) light availability; or (3) the number of conspecifics and heterospecifics in the surrounding neighbourhood. Individual growth rates were positively related to palm height in the three life stages considered here (seedlings, saplings and adults). The mean annual diameter increment was higher (3.2 ± 4.6 mm year−1) in individuals with a diameter at breast height (DBH) of < 20 cm, and mean vertical elongation of juveniles (0.2 ± 0.2 m year−1) was initiated early in development until they became pre-adults. Growth in I. deltoidea was minimally affected by the presence of neighbours (basal area of conspecifics and heterospecifics), suggesting that this species can succeed at high densities with low levels of interspecific competition. Under the forest canopy, growth rates were not significantly different in palms with greater light exposure. Our findings contribute to an understanding of the factors that make I. deltoidea a dominant species in western Amazonia.
The theory of metabolic ecology predicts specific relationships among tree stem diameter, biomass, height, growth and mortality. As demographic rates are important to estimates of carbon fluxes in ...forests, this theory might offer important insights into the global carbon budget, and deserves careful assessment. We assembled data from 10 old‐growth tropical forests encompassing censuses of 367 ha and > 1.7 million trees to test the theory's predictions. We also developed a set of alternative predictions that retained some assumptions of metabolic ecology while also considering how availability of a key limiting resource, light, changes with tree size. Our results show that there are no universal scaling relationships of growth or mortality with size among trees in tropical forests. Observed patterns were consistent with our alternative model in the one site where we had the data necessary to evaluate it, and were inconsistent with the predictions of metabolic ecology in all forests.
Importance of Demographic Niches to Tree Diversity Condit, Richard; Ashton, Peter; Bunyavejchewin, Sarayudh ...
Science (American Association for the Advancement of Science),
07/2006, Volume:
313, Issue:
5783
Journal Article
Peer reviewed
Open access
Most ecological hypotheses about species coexistence hinge on species differences, but quantifying trait differences across species in diverse communities is often unfeasible. We examined the ...variation of demographic traits using a global tropical forest data set covering 4500 species in 10 large-scale tree inventories. With a hierarchical Bayesian approach, we quantified the distribution of mortality and growth rates of all tree species at each site. This allowed us to test the prediction that demographic differences facilitate species richness, as suggested by the theory that a tradeoff between high growth and high survival allows species to coexist. Contrary to the prediction, the most diverse forests had the least demographic variation. Although demographic differences may foster coexistence, they do not explain any of the 16-fold variation in tree species richness observed across the tropics.
Plastic waste is an issue of global concern because of the environmental impact of its accumulation in waste management systems and ecosystems. Biodegradability was proposed as a solution to overcome ...this problem; however, most biodegradable plastics were designed to degrade under aerobic conditions, ideally fulfilled in a composting plant. These new plastics could arrive to anaerobic environments, purposely or frequently, because of their mismanagement at the end of their useful life. This review analyzes the behavior of biodegradable and conventional plastics under anaerobic conditions, specifically in anaerobic digestion systems and landfills. A review was performed in order to identify: (a) the environmental conditions found in anaerobic digestion processes and landfills, as well as the mechanisms for degradation in those environments; (b) the experimental methods used for the assessment of biodegradation in anaerobic conditions; and (c) the extent of the biodegradation process for different plastics. Results show a remarkable variability of the biodegradation rate depending on the type of plastic and experimental conditions, with clearly better performance in anaerobic digestion systems, where temperature, water content, and inoculum are strictly controlled. The majority of the studied plastics showed that thermophilic conditions increase degradation. It should not be assumed that plastics designed to be degraded aerobically will biodegrade under anaerobic conditions, and an exact match must be done between the specific plastics and the end of life options that they will face.
Based on the use of multi-beams, high throughput satellites (HTSs) provide high data rates to a large number of users. In this context, the distribution of frequency resources among multi-beams plays ...an important role. This is because unsuitable distributions might cause the wastage or the starvation of frequencies and bring about low throughput rates. This paper proposes a solution to mitigate the unsuitable allocations of frequency resources in an HTS. The solution is the priority code scheme (PCS), which seeks to respond to users' demands by dynamically scheduling frequency resources for precise satellite footprint areas. The key is to assign a priority code and an efficiency indicator to every multi-beam deployed on the system. The PCS algorithm involves the association of the efficiency indicator with the bandwidth utilization per beam to detect and correct arbitrary bandwidth allocations among the beams. Due to the PCS's cyclical repetition of its algorithm, the concurrence time of the scheme and the tardiness of the algorithm form part of the evaluation of the PCS. Furthermore, we support the implementation of the frequency-reuse process to enhance the exploitation of frequency resources. To evaluate the PCS performance, the analysis delves into the study of the bandwidth utilization, the interference among beams, the concurrence time, and the algorithm tardiness.
PDF
