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排序方式: 共有3023条查询结果,搜索用时 9 毫秒
1.
Federico R Conde M Sandra Churio Carlos M Previtali 《Photochemical & photobiological sciences》2004,3(10):960-967
In vitro studies on the structurally related mycosporine-like amino acids (MAAs) porphyra-334 and shinorine in aqueous solutions were carried out aiming at their full photochemical and photophysical characterization and expanding the evidence on the assigned UV-photoprotective role of the molecules in vivo. The experiments on shinorine confirmed a high photostability and a poor fluorescence quantum yield, in concordance with previous results on porphyra-334. The estimation of triplet production quantum yields for both MAAs was achieved by laser-flash photolysis measurements. In particular, photosensitization experiments on porphyra-334 support the participation of the triplet state in the photodecomposition mechanism yielding a more precise value of [capital Phi](T). As well, photoacoustic calorimetry experiments allowed the first direct quantification of the nonradiative relaxation pathways of the excited MAAs in solution, corroborating that the vast majority (ca. 97%) of the absorbed energy is promptly delivered to the surroundings as heat, consistently with the low photodecomposition and emission yields observed. 相似文献
2.
The effects of d-penicillamine on proliferation and polyclonal activation of lymphocytes were studied in cultures of spleen cells from a variety of murine strains. Inclusion in serum-free or serum-containing medium of optimal concentrations of d-penicillamine resulted in the uptake of tritiated thymidine in a dose-dependent fashion, with both lower and higher doses causing less marked effects. The kinetic peak of these responses was found to occur at Day 2 of culture. Experiments examining the responsiveness of B-cell-enriched and T-cell-enriched populations demonstrated that d-penicillamine, like 2-mercaptoethanol, stimulates both types of cell. The magnitude of the response remained unchanged in populations depleted of adherent cells. In correlation with previous results seen for 2-ME, d-penicillamine was mitogenically active both in reduced and oxidized forms. The oxidized form failed to enhance the response to LPS, in contrast to the marked effect of the reduced form. Additionally, d-penicillamine failed to evoke a mitogenic response from B cells of CBA/N mice, a strain characterized by a deficit in the function of a particular set of mature B cells. Young mice from autoimmune strains responded to d-penicillamine as well as normal mice did. No relationship could be observed between responsiveness to d-penicillamine and the H-2 phenotype of the cell donor, and in A/J mice hyporesponsiveness was shown to be a function of their background rather than H-2. d-Penicillamine was found to function as a polyclonal B-cell activator, and to significantly enhance the primary humoral immune response to sheep erythrocytes in vitro. These immunomodulatory effects of d-penicillamine are discussed in relation to possible pathogenetic mechanisms of its spectrum of autoimmune side effects. 相似文献
3.
R Pozzuoli M Piantelli C Perucci E Arru P Musiani 《Journal of immunology (Baltimore, Md. : 1950)》1975,115(5):1459-1463
This paper describes a simplified procedure for obtaining purified Echinococcus granulosus antigens from sheep hydatid fluid by using affinity chromatography on concanavalin A-Sepharose. The presence of two "major" antigens (4 and 5) was confirmed. Antigen 5 was isolated by preparative polyacrylamide gel electrophoresis. Antigen 4, eluted by diffusion from the gel, was seen to be "contaminated" by antigen 5 and was isolated by using anti-5 Sepharose-linked serum. These two major antigens were then tested separately against the sera of hydatidosis patients by using very simple immunolgic tests. The best results were obtained in passive hemagglutination with antigen 4. Antigen 4 is the most immunoreactive parasitic antigen; antibodies against it were found in the sera of all hydatidosis patients showing positive reaction. Apart from the direct use of this antigen in serologic tests, it appears possible to standarize the most frequently used and commerically available antigenic materials by titrating this component. 相似文献
4.
5.
Wagner A. Chiba de Castro Rafael O. Xavier Federico H. L. Garrido Jair H. C. Romero Cleto K. Peres Ruberval C. da Luz 《Journal of Plant Ecology》2019,12(4):713
Aims
Invasive plants modify the structure and functioning of natural environments and threat native plant communities. Invasive species are often favored by human interference such as the creation of artificial forest edges. Field removal experiments may clarify if invasive plants are detrimental to native plant regeneration and how this is related to other local factors. We assessed the joint effect of environment and competition with the invasiveTradescantia zebrinaon tree species recruitment in an Atlantic Forest fragment. 相似文献
6.
7.
Juan Ignacio Ruiz Kaamel Nuhu Justin Tyler McDaniel Federico Popoff Ariel Izcovich Juan Martin Criniti 《PloS one》2015,10(10)
Background
Maternal and infant mortality are highly devastating, yet, in many cases, preventable events for a community. The human development of a country is a strong predictor of maternal and infant mortality, reflecting the importance of socioeconomic factors in determinants of health. Previous research has shown that the Human Development Index (HDI) predicts infant mortality rate (IMR) and the maternal mortality ratio (MMR). Inequality has also been shown to be associated with worse health in certain populations. The main purpose of the present study was to determine the correlation and predictive power of the Inequality Adjusted Human Development Index (IHDI) as a measure of inequality with the Infant Mortality Rate (IMR), Maternal Mortality Rate (MMR), Early Neonatal Mortality Rate (ENMR), Late Neonatal Mortality Rate (LNMR), and the Post Neonatal Mortality Rate (PNMR).Methods and Findings
Data for the present study were downloaded from two sources: infant and maternal mortality data were downloaded from the Global Burden of Disease 2013 Cause of Death Database and the Human Development Index (HDI) and Inequality-Adjusted Human Development Index (IHDI) data were downloaded from the United Nations Development Program (UNDP). Pearson correlation coefficients were estimated, following logarithmic transformations to the data, to examine the relationship between HDI and IHDI with MMR, IMR, ENMR, LNMR, and PNMR. Steiger’s Z test for the equality of two dependent correlations was utilized in order to determine whether the HDI or IHDI was more strongly associated with the outcome variables. Lastly, we constructed OLS regression models in order to determine the predictive power of the HDI and IHDI in terms of the MMR, IMR, ENMR, LNMR, and PNMR.Maternal and infant mortality were both strongly and negatively correlated with both HDI and IHDI; however, Steiger’s Z test for the equality of two dependent correlations revealed that IHDI was more strongly correlated than HDI with MMR (Z = 4.897, p < 0.001), IMR (Z = 2.524, p = 0.012), ENMR (Z = 2.936, p = 0.003), LNMR (Z = 2.272, p = 0.023), and PNMR (Z = 2.277, p = 0.023). Furthermore, side-by-side OLS regression models revealed that, when IHDI was used as the predictor variable instead of HDI, the R 2 value was 0.053 higher for MMR, 0.025 higher for IMR, 0.038 higher for ENMR, 0.029 higher for LNMR, and 0.026 higher for PNMR.Conclusions
Even when both the HDI and the IHDI correlate with the infant and maternal mortality rates, the IHDI is a better predictor for these two health indicators. Therefore, these results add more evidence that inequality is playing an important role in determining the health status of various populations in the world and more efforts should be put into programs to fight inequality. 相似文献8.
Mugnaini C Manetti F Esté JA Clotet-Codina I Maga G Cancio R Botta M Corelli F 《Bioorganic & medicinal chemistry letters》2006,16(13):3541-3544
S-Aryl-S-DABO derivatives, a novel subclass of S-DABO anti-HIV-1 agents, were synthesized via Ullmann type reaction starting from the corresponding 2-thiouracils by the aid of microwave irradiation. The results of their evaluation as inhibitors of RT are reported together with their antiviral activity in cellular assays. 相似文献
9.
Pyrenean Pastoralists’ Ecological Knowledge: Documentation and Application to Natural Resource Management and Adaptation 总被引:1,自引:0,他引:1
María E. Fernández-Giménez Federico Fillat Estaque 《Human ecology: an interdisciplinary journal》2012,40(2):287-300
Pastoral production systems in the Spanish Pyrenees have changed dramatically in recent decades, leading to the loss of traditional ecological knowledge (TEK). We documented TEK of pastoralists from two valleys in the western Central Pyrenees of Aragón and explored its potential applications to resource management and adaptation. Pyrenean pastoralists possess extensive knowledge of relationships between terrain, climate, vegetation and animal nutrition and behavior. TEK could contribute to sustainable stewardship and facilitate adaptation by informing pasture monitoring; providing traditional practices to manage mountain vegetation; and preserving knowledge of extensive livestock production strategies, such as transhumance. Institutional barriers to applying TEK include weak economic cooperation among stockmen, their dependence on EU subsidies, and lack of voice in regional government decisions about local resources. A more collaborative, place-based stewardship of the Central Pyrenees might begin with direct involvement of pastoralists in designing monitoring of pasture conditions and vegetation type changes. 相似文献
10.
Cem Sievers Tommy Schlumpf Ritwick Sawarkar Federico Comoglio Renato Paro 《Nucleic acids research》2012,40(20):e160
The Photo-Activatable Ribonucleoside-enhanced CrossLinking and ImmunoPrecipitation (PAR-CLIP) method was recently developed for global identification of RNAs interacting with proteins. The strength of this versatile method results from induction of specific T to C transitions at sites of interaction. However, current analytical tools do not distinguish between non-experimentally and experimentally induced transitions. Furthermore, geometric properties at potential binding sites are not taken into account. To surmount these shortcomings, we developed a two-step algorithm consisting of a non-parametric two-component mixture model and a wavelet-based peak calling procedure. Our algorithm can reduce the number of false positives up to 24% thereby identifying high confidence interaction sites. We successfully employed this approach in conjunction with a modified PAR-CLIP protocol to study the functional role of nuclear Moloney leukemia virus 10, a putative RNA helicase interacting with Argonaute2 and Polycomb. Our method, available as the R package wavClusteR, is generally applicable to any substitution-based inference problem in genomics. 相似文献