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31.
Vanessa Silva-Moraes Flávia Fernanda Bubula Couto Marah Mileib Vasconcelos Neusa Araújo Paulo Marcos Zech Coelho Naftale Katz Rafaella Fortini Queiroz Grenfell 《Memórias do Instituto Oswaldo Cruz》2013,108(5):600-604
Current schistosomiasis control strategies are largely based on chemotherapeutic
agents and a limited number of drugs are available today. Praziquantel (PZQ) is
the only drug currently used in schistosomiasis control programs. Unfortunately,
this drug shows poor efficacy in patients during the earliest infection phases.
The effects of PZQ appear to operate on the voltage-operated Ca2+channels, which
are located on the external Schistosoma mansoni membrane.
Because some Ca2+channels have dihydropyridine drug class (a class that includes
nifedipine) sensitivity, an in vitro analysis using a calcium channel antagonist
(clinically used for cardiovascular hypertension) was performed to determine the
antischistosomal effects of nifedipine on schistosomula and adult worm cultures.
Nifedipine demonstrated antischistosomal activity against schistosomula and
significantly reduced viability at all of the concentrations used alone or in
combination with PZQ. In contrast, PZQ did not show significant efficacy when
used alone. Adult worms were also affected by nifedipine after a 24 h incubation
and exhibited impaired motility, several lesions on the tegument and intense
contractility. These data support the idea of Ca2+channels subunits as drug
targets and favour alternative therapeutic schemes when drug resistance has been
reported. In this paper, strong arguments encouraging drug research are
presented, with a focus on exploring schistosomal Ca2+channels. 相似文献
32.
Daniela Goeten Gladys D. Rogge-Renner der C. Schmidt Zenilda L. Bouzon Francine L. Farias-Soares Miguel P. Guerra Neusa Steiner 《Protoplasma》2020,257(3):931-948
This study addresses gaps in our understanding of pre-fertilization and archegonia development and reinterprets embryonic ontogenesis from Burlingame (Bot Gaz 59:1–39, 1915) to the present based on timescale and structural features allowing us to determine functionally and developmentally accurate terminology for all these stages in A. angustifolia. Different from previous reports, only after pollination, pre-fertilization tissue development occurs (0–13 months after pollination (MAP)) and gives rise to a mature megagametophyte. During all this period, pollen is in a dormant state at the microphyla, and pollen tube germination in nucellus tissue is only observed at the stage of archegonia formation (13 MAP) and not at the free nuclei stage as reported before. For the first time, 14 months after pollination, a fertilization window was indicated, and at 15 MAP, the polyzygotic polyembryony from different archegonia was also seen. After that, subordinated proembryo regression occurs and at least three embryonic developmental stages of dominant embryo were characterized: proembryogenic, early embryogenic, and late embryogenic (15–23 MAP). Along these stages, histochemical and ultrastructural analyses suggest the occurrence of cell death in suspensor and in cap cells of dominant embryo that was not previously reported. The differentiation of meristems, procambium, pith, and cortex tissues in late embryogenic stage was detailed. The morphohistological characterization of pre-fertilization and embryonic stages, together with the timescale of megastrobili development, warranted a referential map of female reproductive structure in this species. 相似文献
33.
Maria Carolina Andrade Nascimento-Gavioli Gabriela Claudia Cangahuala-Inocente Douglas Steinmacher Joseph Francis Ree Neusa Steiner Miguel Pedro Guerra 《In vitro cellular & developmental biology. Plant》2017,53(1):33-40
Both embryogenic and non-embryogenic peach palm (Bactris gasipaes Kunth) cultures arise during somatic embryogenesis induction, and both tissue types are often observed growing side-by-side from the same explant. To better understand why this occurs, samples from each tissue type were analyzed for their endogenous concentrations of indole-3-acetic acid (IAA), abscisic acid (ABA), polyamines, and amino acids with high-performance liquid chromatography and for total phenolics with spectrophotometry. Embryogenic cultures contained significantly higher concentrations of IAA, ABA, and total amino acids, whereas non-embryogenic tissue contained more total polyamines and phenolics. The greater IAA concentrations in embryogenic cultures supported the role of that hormone as a marker of embryogenic potential. Putrescine was especially prevalent in non-embryogenic cultures; however, the decreased putrescine/spermine + spermidine ratio in embryogenic cultures added support to the conclusions of previous studies in other species that this can serve as a marker of embryogenic competence. Though embryogenic cultures contained higher total amino acids, each culture type had different concentrations of specific amino acids. 相似文献
34.
Species richness and spatial distribution of blackflies (Diptera: Simuliidae) in streams of Central Amazonia, Brazil 总被引:2,自引:0,他引:2
1. The spatial distribution and species richness of blackflies were evaluated at 58 stream sites in Central Amazonia, Brazil. Samples were taken along a north–south axis of approximately 130 km and a east–west axis of approximately 220 km.
2. Based on stream-site characteristics, the occurrence of larvae of the six most frequently collected species was highly predictable (79.3–91.5% accuracy in prediction of occurrence). The predictive value of stream size and the presence of impoundments agrees with results of similar work in the Holarctic Region, suggesting a general responses of blackflies to environmental parameters.
3. Although only 19.0% of interstream variation in species richness was explained by a regression model, results suggested that species richness was greater in larger, cooler, faster, covered streams with rocky beds than in smaller, warmer, slower, open streams with sandy bottoms. Overall, the species richness of blackflies (11 species in total) was lower than in the temperate zone suggesting, for some taxa at least, that aquatic communities do not follow the terrestrial pattern of greater species richness in the tropics. 相似文献
2. Based on stream-site characteristics, the occurrence of larvae of the six most frequently collected species was highly predictable (79.3–91.5% accuracy in prediction of occurrence). The predictive value of stream size and the presence of impoundments agrees with results of similar work in the Holarctic Region, suggesting a general responses of blackflies to environmental parameters.
3. Although only 19.0% of interstream variation in species richness was explained by a regression model, results suggested that species richness was greater in larger, cooler, faster, covered streams with rocky beds than in smaller, warmer, slower, open streams with sandy bottoms. Overall, the species richness of blackflies (11 species in total) was lower than in the temperate zone suggesting, for some taxa at least, that aquatic communities do not follow the terrestrial pattern of greater species richness in the tropics. 相似文献
35.
The larva, pupa, male, and female of Simulium bifenestratum n. sp. are described and illustrated. The pupae of the new species have 10 gill filaments, thick at their base and arranged in a three-dimensional way, surrounding the head and thorax. Its pupal cocoon is peculiar, not found in any of the known Brazilian black-fly species; it is very thick and hard with two openings in the anterior region. S. bifenestratum n. sp. was collected in one stream in the Bocaina mountain chain, Atlantic forest, in S?o José do Barreiro county, state of S?o Paulo, in a high (1500 m) natural grassland. Larvae and pupae were collected on the edges of small waterfalls and in places with-high speed laminar water flow, attached to the bedrock. 相似文献
36.
Apoptotic cell death plays a critical role in immune system homeostasis, and c-myc protooncogene deregulated expression is a component of this programmed genomic response. Pharmacological intervention and modulation of peripheral lymphocytes apoptosis would have important implications. The present results indicate that ouabain, a specific inhibitor of Na+K+-ATPase, promotes an increased expression of c-myc mRNA, and induces apoptosis in PHA-stimulated lymphocytes. Furthermore, this ouabain-induced apoptosis cannot be counteracted by the addition of exogenous IL-2. 相似文献
37.
Leaf breakdown in streams is affected by several factors, such as leaf characteristics, water chemistry, microbial activity,
and abundance of shredders. In turn, shredders may be resource-controlled. We hypothesized that the size of litter patches
affects leaf breakdown, because large patches should be stable over time and therefore harbor high densities of shredders.
We selected litter patches (area 0.25–10 m2) in 10 pools of three first-order streams (Manaus, Brazil). We installed 10 leaf packs of Mabea
speciosa (Euphorbiaceae) in each patch, and sampled one after 1 day and three after 5, 19, and 28 days. The leaf packs were quickly
colonized by the shredding caddisflies Triplectides and Phylloicus. The leaf breakdown rate (mean k = 0.026 ± 0.0015 SE) was high and similar to values reported for other tropical and temperate streams, although much higher
than values reported for the adjacent Cerrado biome. Assemblage composition varied over time, but was not related to the size
of litter patches. Contrary to our hypothesis, litter patch area did not affect breakdown rates (r
2 = 0.012, P = 0.766) or abundance of shredders after 5, 19, and 28 days (r
2 < 0.243, P > 0.147). We found, however, a positive relationship between the abundance of tropical shredders and leaf breakdown after
19 days (r
2 = 0.572, P = 0.011), suggesting that shredders play an important role in leaf breakdown in these headwater streams. Our study indicates
that leaf breakdown rates in tropical streams are variable and can be as high as those of temperate streams. 相似文献
38.
Matheus H. O. de Sousa Jessica M. S. Morgan Karina Cesca Adriana Flach Neusa F. de Moura 《化学与生物多样性》2020,17(2)
The Cunila angustifolia essential oil was obtained from fresh leaves by hydrodistillation and analyzed by GC‐FID and GC‐MS to determine its chemical composition. The essential oil presented pulegone (29.5 %) and isomenthol (27.0 %) as major components, and other compounds such as menthone (8.6 %), neomenthol (7.2 %), menthyl acetate (2.5 %) and caryophyllene oxide (2.0 %) were identified. The cytotoxic activity of the essential oil was evaluated by MTS assay, with the human cancer cell lines of the lung (A549), breast (MCF‐7) and skin melanoma (SK‐Mel‐28). The assay showed the highest selectivity, to MCF‐7 cell lines, with IC50 equal to 34.0 μg mL?1, low selectivity for SK‐Mel‐28 cell lines, with IC50 equal to 279.9 μg mL?1, and no mortality to A549 cell lines. 相似文献
39.
Andréa Cássia Sim?es Vimieiro Neusa Araújo Naftale Katz John Robert Kusel Paulo Marcos Zech Coelho 《Memórias do Instituto Oswaldo Cruz》2013,108(7):881-886
Mice infected with Schistosoma mansoni were treated with oxamniquine, praziquantel, artesunate at the pre-patent phase, aiming at observing schistogram alterations. Half of the animals were perfused five days post-treatment for counting and classification of immature worms, based on pre-established morphological criteria (schistogram); the remaining animals were evaluated 42 or 100 days after infection and perfusion of the portal-system was performed for collection and counting of adult worms and oogram. It was observed that oxamniquine and artesunate treatment administered at the pre-postural phase causes significant reduction in the number of immature and adult worms. However, there was little reduction with praziquantel when used at the dose of 400 mg/kg for treatments administered 14, 15, 21 or 23 days post-infection. Artesunate was responsible for significant alterations in development of young worms, as well as for a higher number of worms presenting intestinal damages. Immature adult worms were detected in mice treated with artesunate or oxamniquine at the pre-patent phase of infection and recovered by perfusion 100 days after infection. Schistogram proved to be a very useful tool for experimental evaluation of the activity of antischistosomal drugs and a good model to identify the most sensitive stages to drugs. 相似文献
40.
Limnology - Natural fluctuations in ecosystems, such as those associated with climate, are a fundamental factor structuring macroinvertebrate assemblages. Given that macroinvertebrates are widely... 相似文献