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981.
982.
Understanding nutrient limitation of net primary productivity (NPP) is critical to predict how plant communities will respond to environmental change. Foliar nutrients, especially nitrogen and phosphorus concentrations ([N] and [P]) and their ratio, have been used widely as indicators of plant nutritional status and have been linked directly to nutrient limitation of NPP. In tropical systems, however, a high number of confounding factors can limit the ability to predict nutrient limitation —as defined mechanistically by NPP responses to fertilization— based on the stoichiometric signal of the plant community. We used a long-term full factorial N and P fertilization experiment in a lowland tropical wet forest in Costa Rica to explore how tissue (foliar, litter and root) [N] and [P] changed with fertilization, how different tree size classes and taxa influenced the community response, and how tissue nutrients related to NPP. Consistent with NPP responses to fertilization, there were no changes in community-wide foliar [N] and [P], two years after fertilization. Nevertheless, litterfall [N] increased with N additions and root [P] increased with P additions. The most common tree species (Pentaclethra macroloba) had 9 % higher mean foliar [N] with NP additions and the most common palm species (Socratea exohrriza) had 15% and 19% higher mean foliar [P] with P and NP additions, respectively. Moreover, N:P ratios were not indicative of NPP responses to fertilization, either at the community or at the taxa level. Our study suggests that in these diverse tropical forests, tissue [N] and [P] are driven by the interaction of multiple factors and are not always indicative of the nutritional status of the plant community. 相似文献
983.
Ana Paula Ribeiro Silvia Maria Amado Jo?o Roberto Casanova Dinato Vitor Daniel Tessutti Isabel Camargo Neves Sacco 《PloS one》2015,10(9)
Aim/Hypothesis
The etiology of plantar fasciitis (PF) has been related to several risk factors, but the magnitude of the plantar load is the most commonly described factor. Although PF is the third most-common injury in runners, only two studies have investigated this factor in runners, and their results are still inconclusive regarding the injury stage.Objective
Analyze and compare the plantar loads and vertical loading rate during running of runners in the acute stage of PF to those in the chronic stage of the injury in relation to healthy runners.Methods
Forty-five runners with unilateral PF (30 acute and 15 chronic) and 30 healthy control runners were evaluated while running at 12 km/h for 40 meters wearing standardized running shoes and Pedar-X insoles. The contact area and time, maximum force, and force-time integral over the rearfoot, midfoot, and forefoot were recorded and the loading rate (20–80% of the first vertical peak) was calculated. Groups were compared by ANOVAs (p<0.05).Results
Maximum force and force-time integral over the rearfoot and the loading rate was higher in runners with PF (acute and chronic) compared with controls (p<0.01). Runners with PF in the acute stage showed lower loading rate and maximum force over the rearfoot compared to runners in the chronic stage (p<0.01).Conclusion
Runners with PF showed different dynamic patterns of plantar loads during running over the rearfoot area depending on the injury stage (acute or chronic). In the acute stage of PF, runners presented lower loading rate and forces over the rearfoot, possibly due to dynamic mechanisms related to pain protection of the calcaneal area. 相似文献984.
985.
986.
Interactions between quercetin and Warfarin for albumin binding: A new eye on food/drug interference
The interaction between quercetin, a popular antioxidant flavonoid, and human serum albumin (HSA) is investigated and characterized by means of induced circular dichroism and saturation transfer difference NMR. These techiques demonstrate the reversible binding of quercetin to the carrier protein, which is responsible for its dissolution in aqueous medium. Competition experiments with two classical probes for HSA binding sites, namely Ibuprofen and Warfarin (a common anticoagulant coumarin), demonstrate that quercetin has a primary binding site located in the subdomain IIA, where coumarins are hosted. The affinity for this site is large and we found that quercetin may effectively displace warfarin from HSA. This may have relevant consequences in rationalizing the interferences of common dietary compounds and food supplements to anticoagulant treatments. Chirality, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
987.
Inés Infante Maria A. Morel Martha C. Ubalde Cecilia Martínez-Rosales Silvia Belvisi Susana Castro-Sowinski 《World journal of microbiology & biotechnology》2010,26(6):1047-1052
Wool is a natural animal fiber commonly used in fabrics, but requires physical and chemical processing treatment for such
applications. With the aim of developing new woollen textile products using environmentally friendly treatments, proteolytic
bacteria were isolated from raw wool samples of Merino sheep and screened for wool-degrading activity. Two isolates were identified as Bacillus megaterium L4 and Bacillus thuringiensis L11 by 16S rRNA gene sequence analysis. Both isolates grew on a minimal medium using wool-fiber or wool-fabric as sole carbon
and nitrogen sources. Bacterial growth was correlated with extracellular protease activity, and maximal protease production
was in early stationary phase. The exoprotease produced by L11 was found to be a thermo-tolerant metalloprotease stabilized
by calcium or magnesium, and had optimum activity at pH 7.0 and temperature at 40°C. During bacterial growth the wool-fiber
lost weight, but it did not show changes in diameter. When wool-fabric was used instead of wool-fiber weight loss and non-shrinking
was found. These are encouraging results for textile processing that should be useful for development of new textile products
by direct microbial processing. A potential alternative that could be suggested from our study would be to treat wool with
wool-degrading microorganisms in order to develop environmentally friendly processes. 相似文献
988.
989.
Mariana Conte Silvia de Simone Susan J Simmons Carlos L Ballaré Ann E Stapleton 《BMC plant biology》2010,10(1):112
Background
Understanding of the genetic architecture of plant UV-B responses allows extensive targeted testing of candidate genes or regions, along with combinations of those genes, for placement in metabolic or signal transduction pathways. 相似文献990.
Giuseppina Sandri Maria Cristina Bonferoni Silvia Rossi Franca Ferrari Cinzia Boselli Carla Caramella 《AAPS PharmSciTech》2010,11(1):362-371
The aim of this paper was to evaluate the penetration enhancement properties of nanoparticles (NP) based on N-trimethyl chitosan (TMC 35% quaternization degree) loaded with insulin. The permeation performances of TMC NP were compared
with those of chitosan (CS) NP and also with TMC and CS solutions. To estimate the mechanism of penetration enhancement, two
different approaches have been taken into account: an in vitro study (Caco-2 cells) and an ex vivo study (excised rat duodenum, jejunum, and ileum). Insulin-loaded CS and TMC NP had dimensions of about 250 nm and had high
yield and high encapsulation efficiency. The in vitro study evidenced that TMC and CS were able to enhance insulin permeation to the same extent. Penetration enhancement properties
of TMC NP seem to be prevalently related to endocytosis while the widening of tight junctions appeared more important as mechanism
in the case of CS NP. The ex vivo study put in evidence the role of mucus layer and of its microclimate pH. In duodenum (pH 5–5.5), CS and TMC solutions were
more effective than NP while TMC NP were more efficient towards jejunum tissue (pH 6–6.5) for their high mucoadhesive potential.
Confocal laser scanning microscopy study supported the hypothesis that penetration enhancement due to TMC NP was mainly due
to internalization/endocytosis into duodenum and jejunum epithelial cells. The good penetration enhancement properties (permeation
and penetration/internalization) make TMC NP suitable carriers for oral administration of insulin. 相似文献