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排序方式: 共有4793条查询结果,搜索用时 15 毫秒
941.
A M Da-Cruz D V Filgueiras Z Coutinho W Mayrink G Grimaldi P M De Luca S C Mendonca S G Coutinho 《Memórias do Instituto Oswaldo Cruz》1999,94(4):537-542
An atypical case of acquired immunodeficiency syndrome-associated mucocutaneous lesions due to Leishmania braziliensis is described. Many vacuolated macrophages laden with amastigote forms of the parasite were found in the lesions. Leishmanin skin test and serology for leishmaniasis were both negative. The patient was resistant to therapy with conventional drugs (antimonial and amphotericin B). Interestingly, remission of lesions was achieved after an alternative combined therapy of antimonial associated with immunotherapy (whole promastigote antigens). Peripheral blood mononuclear cells were separated and stimulated in vitro with Leishmania antigens to test the lymphoproliferative responses (LPR). Before the combined immunochemotherapy, the LPR to leishmanial antigens was negligible (stimulation index - SI=1.4). After the first course of combined therapy it became positive (SI=4.17). The antigen responding cells were predominantly T-cells (47.5%) most of them with CD8+ phenotype (33%). Very low CD4+ cells (2.2%) percentages were detected. The increased T-cell responsiveness to leishmanial antigens after combined therapy was accompanied by interferon-g (IFN-g) production as observed in the cell culture supernatants. In this patient, healing of the leishmaniasis lesions was associated with the induction of a specific T-cell immune response, characterized by the production of IFN-g and the predominance of the CD8+ phenotype among the Leishmania-reactive T-cells. 相似文献
942.
Andel M. Conradie Luca D. Bertzbach Jakob Trimpert Joseph N. Patria Shiro Murata Mark S. Parcells Benedikt B. Kaufer 《PLoS pathogens》2020,16(12)
Modified-live herpesvirus vaccines are widely used in humans and animals, but field strains can emerge that have a higher virulence and break vaccinal protection. Since the introduction of the first vaccine in the 1970s, Marek’s disease virus overcame the vaccine barrier by the acquisition of numerous genomic mutations. However, the evolutionary adaptations in the herpesvirus genome responsible for the vaccine breaks have remained elusive. Here, we demonstrate that point mutations in the multifunctional meq gene acquired during evolution can significantly alter virulence. Defined mutations found in highly virulent strains also allowed the virus to overcome innate cellular responses and vaccinal protection. Concomitantly, the adaptations in meq enhanced virus shedding into the environment, likely providing a selective advantage for the virus. Our study provides the first experimental evidence that few point mutations in a single herpesviral gene result in drastically increased virulence, enhanced shedding, and escape from vaccinal protection. 相似文献
943.
Giacomucci Antonio Baldo Gian Luca 《The International Journal of Life Cycle Assessment》1999,4(3):165-166
The International Journal of Life Cycle Assessment - 相似文献
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946.
Ahmed Kassab Luca Sabatini Gidon Lieberman Amanda Tozer Ariel Zosmer Colin Davis Talha Al-Shawaf 《Reproductive biology and endocrinology : RB&E》2007,5(1):32-6
Background
The aim was to examine the correlation of early follicular serum lutinising hormone (LH) and the clinical outcome of assisted reproduction technique (ART). 相似文献947.
The biomechanical management of bioenergetics of runners when running uphill was investigated. Several metabolic and mechanical variables have been studied simultaneously to spread light on the locomotory strategy operated by humans for effective locomotion. The studied variables were: heart rate, heart rate variability, oxygen intake and blood lactate, metabolic cost, kinematics, ground reaction force and muscular activity. 18 high-level competitive male runners ran at 70% VO2max on different uphill slope conditions: 0%, 2% and 7%. Modifications were significant in almost all variables studied, and were more pronounced with increasing incline. Step frequency/length and ground reaction force are adjusted to cope with both the task of uphill progression and the available (limited) metabolic power. From 0% to 7% slope, step frequency and ground reaction force and metabolic cost increased concurrently by 4%, 12% and 53%, respectively (with a 4% step length decrease as well). It is hypothesised that this biomechanical management is allowed by an environment-body communication performed by means of specific muscular activity. 相似文献
948.
Y Ragazzoni M Desideri C Gabellini T De Luca S Carradori D Secci R Nescatelli A Candiloro M Condello S Meschini D Del Bufalo D Trisciuoglio 《Cell death & disease》2013,4(3):e524
We have previously demonstrated that the thiazole derivative 3-methylcyclopentylidene-[4-(4′-chlorophenyl)thiazol-2-yl]hydrazone (CPTH6) induces apoptosis and cell cycle arrest in human leukemia cells. The aim of this study was to evaluate whether CPTH6 is able to affect autophagy. By using several human tumor cell lines with different origins we demonstrated that CPTH6 treatment induced, in a dose-dependent manner, a significant increase in autophagic features, as imaged by electron microscopy, immunoblotting analysis of membrane-bound form of microtubule-associated protein 1 light chain 3 (LC3B-II) levels and by appearance of typical LC3B-II-associated autophagosomal puncta. To gain insights into the molecular mechanisms of elevated markers of autophagy induced by CPTH6 treatment, we silenced the expression of several proteins acting at different steps of autophagy. We found that the effect of CPTH6 on autophagy developed through a noncanonical mechanism that did not require beclin-1-dependent nucleation, but involved Atg-7-mediated elongation of autophagosomal membranes. Strikingly, a combined treatment of CPTH6 with late-stage autophagy inhibitors, such as chloroquine and bafilomycin A1, demonstrates that under basal condition CPTH6 reduces autophagosome turnover through an impairment of their degradation pathway, rather than enhancing autophagosome formation, as confirmed by immunofluorescence experiments. According to these results, CPTH6-induced enhancement of autophagy substrate p62 and NBR1 protein levels confirms a blockage of autophagic cargo degradation. In addition, CPTH6 inhibited autophagosome maturation and compounds having high structural similarities with CPTH6 produced similar effects on the autophagic pathway. Finally, the evidence that CPTH6 treatment decreased α-tubulin acetylation and failed to increase autophagic markers in cells in which acetyltransferase ATAT1 expression was silenced indicates a possible role of α-tubulin acetylation in CPTH6-induced alteration in autophagy. Overall, CPTH6 could be a valuable agent for the treatment of cancer and should be further studied as a possible antineoplastic agent. 相似文献
949.
Giovanni Luca Ciampaglia Prashant Shiralkar Luis M. Rocha Johan Bollen Filippo Menczer Alessandro Flammini 《PloS one》2015,10(6)
Traditional fact checking by expert journalists cannot keep up with the enormous volume of information that is now generated online. Computational fact checking may significantly enhance our ability to evaluate the veracity of dubious information. Here we show that the complexities of human fact checking can be approximated quite well by finding the shortest path between concept nodes under properly defined semantic proximity metrics on knowledge graphs. Framed as a network problem this approach is feasible with efficient computational techniques. We evaluate this approach by examining tens of thousands of claims related to history, entertainment, geography, and biographical information using a public knowledge graph extracted from Wikipedia. Statements independently known to be true consistently receive higher support via our method than do false ones. These findings represent a significant step toward scalable computational fact-checking methods that may one day mitigate the spread of harmful misinformation. 相似文献
950.
Isolation and Characterization of a 2-Oxoglutarate Dependent Dioxygenase Involved in the Second-to-Last Step in Vindoline Biosynthesis 总被引:4,自引:2,他引:2
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Young leaves from Catharanthus roseus plants contain the enzymes which convert the monoterpenoid indole alkaloid, tabersonine by three hydroxylations, two methylations, and one acetylation step to vindoline. A novel direct enzyme assay has been developed for a hydroxylase involved in vindoline biosynthesis, which catalyzes the C4-hydroxylation of 2,3-dihydro-3-hydroxy-N(1)-methyltabersonine to the 3,4-dihydroxy derivative. The enzyme showed an absolute requirement for 2-oxoglutarate and enzymatic activity was enhanced by ascorbate, establishing it as a 2-oxoglutarate-dependent dioxygenase (EC 1.14.11.-). The hydroxylase exhibited specificity for position 4 of various alkaloid substrates. The enzyme exhibited a pH optima between 7 and 8 and an apparent molecular weight of 45,000. The appearance of 4-hydroxylase activity was developmentally regulated and was shown to be inducible by light treatment of seedlings. Substrate specificity studies of this enzyme for indole alkaloid substrate suggested that hydroxylation at position 3 and N-methylation occur prior to hydroxylation at position 4. This is in agreement with previous studies which suggest that C4-hydroxylation is the second to last step in vindoline biosynthesis in Catharanthus roseus. 相似文献