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61.
Azevedo Dde O Matiello-Guss CP Rönnau M Zanuncio JC Serrão JE 《Microscopy research and technique》2008,71(3):196-200
The sensilla are sensory organs formed by cuticular and cellular structures specialized in reception of chemical and physical stimuli from the environment and transmission to the insect's central nervous system. In function of the great concentration of sensilla, the antennae are the main organs for interaction between bees and with the environment. This work studied the presence of antennal sensilla in the different phases of pupal development of the stingless bee Melipona quadrifasciata anthidioides by means of scanning electron microscopy and light microscopy. The results showed that antennal sensilla begin their development in the transition of the prepupae to the white-eyed pupae and finish it in the pigmented-body pupae phase. The antennal sensilla were exposed to the environment in the black-eyed pupae when the old cuticle is completely digested, suggesting that only in the final pupal phases can these bees perceive the environmental stimuli. 相似文献
62.
Sant'Anna C Pereira MG Lemgruber L de Souza W Cunha e Silva NL 《Microscopy research and technique》2008,71(8):599-605
Reservosomes are late endosomes present only in members of the Schizotrypanum subgenus of the Trypanosoma genus and are defined as the site of storage of endocytosed macromolecules and lysosomal enzymes. They have been extensively described in Trypanosoma cruzi epimastigote: are bounded by a membrane unit, present an electron-dense protein matrix with electron-lucent lipid inclusions, being devoid of inner membranes. Here we performed a detailed ultrastructural analysis of these organelles using a variety of electron microscopy techniques, including ultrathin sectioning, uranyl acetate stained preparations, and freeze fracture, either in intact epimastigotes or in isolated reservosomes. New informations were obtained. First, both isolated and in situ reservosomes presented small profiles of inner membranes that are morphologically similar to the membrane surrounding the organelle. In uranyl acetate stained preparations, internal membrane profiles turned out to be longer than they appeared in ultrathin section images and traversed the organelle diameter. Internal vesicles were also found. Second, endocytosed cargo are not associated with internal vesicles and reach reservosomes on board of vesicles that fuse with the boundary membrane, delivering cargo directly into reservosome lumen. Third, electron-lucent bodies with saturated lipid core surrounded by a membrane monolayer and with unusual rectangular shape were also observed. Fourth, it was possible to demonstrate the presence of intramembranous particles on the E face of both internal vesicles and the surrounding membrane. Collectively, these results indicate that reservosomes have a complex internal structure, which may correlate with their multiple functions. 相似文献
63.
One of the major obstacles of chemotherapy is that, after repeated treatments, cellular resistance to the drug appears. The problem is that the tumor cells become resistant not only to the drugs which have been used during the treatment but also to other drugs which are structurally and functionally unrelated. This is termed 'multidrug resistance' (MDR). MDR is frequently associated with decreased drug accumulation resulting from enhanced drug efflux. This is correlated with the presence of a membrane protein, P-glycoprotein, which pumps a wide variety of drugs out of cells thus reducing their toxicity. The search for molecules able to reverse MDR is very important. We here report that mobile ionophores such as valinomycin, nonactin, nigericin, monensin, calcimycin, lasalocid inhibit the efflux of anthracycline by P-glycoprotein whereas, channel-forming ionophores such as gramicidin do not. Cyclosporin which is also a strong Ca(2+) chelating agent also inhibits the P-glycoprotein-mediated efflux of anthracycline. 相似文献
64.
Cássia A. Glasser Marta M. D. C. Vila Júlio C. Pereira Marco V. Chaud José M. Oliveira Júnior Matthieu Tubino 《Drug development and industrial pharmacy》2016,42(12):1990-2000
The aqueous-core enclosed in lipid nanoballoons integrating multiple emulsions of the type water-in-oil-in-water mimic, at least in theory, the environment within viable cells, thus being suitable for housing hydrophilic protein entities such as bioactive proteins, peptides and bacteriophage particles. This study reports a complete physicochemical characterization of optimized biomimetic aqueous-core lipid nanoballoons housing hydrophilic (BSA) protein entities, evolved from a statistical 23×31 factorial design study (three variables at two levels and one variable at three levels) that was the subject of the first paper of a series of three, aiming at complete stabilization of the three-dimensional structure of protein entities attempted via housing the said molecular entities within biomimetic aqueous-core lipid nanoballoons integrating a multiple (W/O/W) emulsion. The statistical factorial design followed led to the production of an optimum W/O/W multiple emulsion possessing quite homogeneous particles with an average hydrodynamic size of (186.2?±?2.6) nm and average Zeta potential of (?36.5?±?0.9) mV, and exhibiting a polydispersity index of 0.206?±?0.014. Additionally, the results obtained for the diffusion coefficient of the lipid nanoballoons integrating the optimized W/O/W multiple emulsion were comparable and of the same order of magnitude (10?12 m2 s?1) as those published by other authors since, typically, diffusion coefficients for molecules range from 10?10 to 10?7 m2 s?1, but diffusion coefficients for nanoparticles are typically of the order of magnitude of 10?12 m2 s?1. 相似文献
65.
66.
A Castro Beiras JL Escudero Pereira A Juffe Stein CM Sánchez J Caramés Bouzán 《Canadian Metallurgical Quarterly》1998,51(8):611-619
The present work describes the process by which the pilot project of clinical management of the Hospital Complex Juan Canalejo, designated as "Heart Area", was implemented. In the first section, the needs and reasons that led to the undertaking of this project are explained. The project's objectives and operative strategies are listed. In the Material and Methods section, three basic aspects of the "Heart Area" are described: selection criteria of the "Area", its structure and function, and its foundation and development. In the Results section, we compare the activity undertaken in the "Area" to the situation present prior to its implementation, in relation to quality and costs. Finally, in the Conclusions, we comment on the important implications that our project can have within the Hospital Complex Juan Canalejo as well as in the health care field in general. 相似文献
67.
Clara Comuzzi Giuliano Dolcetti Alessandro Trovarelli Fabrizio Cavani Ferruccio Trifirò Jordi Llorca Richard G. Finke 《Catalysis Letters》1996,36(1-2):75-79
The thermal and structural stability of the Wells-Dawson-type heteropoly compound K6P2W18O62·10H2O was examined by FT-IR spectroscopy, X-ray powder diffraction, thermogravimetric analysis and HRTEM. It was found that calcination at temperatures higher than 850 K led to the formation of a Keggin-type compound K3PW12O40, containing small amounts of an additional phase originated from the high-temperature interaction between potassium phosphate (K3PO4 formed during the decomposition of the K6P2W18O62·10H2O) and the Keggin-type compound itself. The Keggin-type product showed a higher activity in the selective oxidative dehydrogenation of isobutane to isobutene compared to both the Wells-Dawson precursor and to pure, authentic K3PW12O40. This higher activity can be tentatively attributed to the presence of an amorphous layer of unknown stoichiometry at the surface of the thermally rearranged Wells-Dawson compound. 相似文献
68.
S Sundaram TW Barrett KB Meyer C Perrella MC Neto AJ King BJ Pereira 《Canadian Metallurgical Quarterly》1996,7(10):2183-2191
The widespread use of bicarbonate dialysate and reprocessed high-efficiency and "high-flux" dialyzers has raised concerns about the increased risk of reverse-transfer of dialysate contaminants into the blood compartment. To evaluate this concern, the reverse-transfer of bacterial products from contaminated bicarbonate dialysate into the blood compartment was compared during in vitro dialysis with new or reprocessed high-flux polysulfone dialyzers. In vitro dialysis was carried out at 37 degrees C by use of a counter-current recirculating loop dialysis circuit with either new high-flux polysulfone dialyzers or dialyzers reprocessed once or 20 times with formaldehyde (0.75%) and bleach (< 1%) with an automated system. Heparinized whole blood from healthy volunteers was circulated through the blood compartment, and bicarbonate dialysate was circulated in the dialysate compartment. The dialysate was challenged sequentially by 1:1000 and 1:100 dilutions of a sterile Pseudomonas aeruginosa culture supernatant (bacterial challenge). Samples were drawn from the blood and dialysate compartments 1 h after each challenge. Peripheral blood mononuclear cells (PBMC) were harvested by Ficoll-Hypaque separation from whole blood in the blood compartment and a 5 x 10(6) PBMC/mL cell suspension was prepared. Likewise, dialysate samples (0.5 mL) were added to 0.5 mL suspension of 5 x 10(6) PBMC/mL drawn at baseline. All PBMC suspensions were incubated upright in a humidified atmosphere at 37 degrees C with 5% CO2 for 24 h, and total interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF alpha) cytokine production (cell-associated and secreted) was measured by radioimmunoassay. Eight experiments were performed for each arm of the study with the same donor for each arm. One hour after contaminating the dialysate with a 1:1000 dilution of the bacterial challenge, IL-1 alpha production by PBMC harvested from the blood compartment was 160 +/- 0, 171 +/- 11, and 270 +/- 35 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.004). One hour after challenging the dialysate with 1:100 dilution, IL-1 alpha production by PBMC harvested from the blood compartment was 188 +/- 20, 228 +/- 35, and 427 +/- 67 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.006). IL-1 alpha production by PBMC from dialyzers reprocessed 20 times was significantly greater than both new and dialyzers reprocessed once. However, there were no significant differences between new dialyzers and dialyzers reprocessed once. Similarly, after the 1:1000 challenge, TNF alpha production by PBMC harvested from the blood compartment was 160 +/- 0, 160 +/- 0, and 213 +/- 22 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.008). After the 1:100 challenge, TNF alpha production was 168 +/- 8, 188 +/- 20, and 225 +/- 32 pg, respectively, for new dialyzers, dialyzers reprocessed once, and dialyzers reprocessed 20 times (P = 0.20). These results demonstrate that reprocessing of high-flux polysulfone dialyzers with bleach increases the risk of reverse-transfer of bacterial products from contaminated dialysate, and this risk appears to increase with the number of reuses. Consequently, units that reprocess membranes with bleach and have suboptimal water quality might subject their patients to a higher risk of cytokine-related morbidity. 相似文献
69.
Marco Alberti Pierangelo Dell��Acqua Lu��s Moniz Pereira 《Annals of Mathematics and Artificial Intelligence》2011,62(3-4):161-186
Many applications (such as system and user monitoring, runtime verification, diagnosis, observation-based decision making, intention recognition) all require to detect the occurrence of an event in a system, which entails the ability to observe the system. Observation can be costly, so it makes sense to try and reduce the number of observations, without losing full certainty about the event??s actual occurrence. In this paper, we propose a formalization of this problem. We formally show that, whenever the event to be detected follows a discrete spatial or temporal pattern, then it is possible to reduce the number of observations. We discuss exact and approximate algorithms to solve the problem, and provide an experimental evaluation of them. We apply the resulting algorithms to verification of linear temporal logics formulæ. Finally, we discuss possible generalizations and extensions, and, in particular, how event detection can benefit from logic programming techniques. 相似文献
70.
André Maués Brabo Pereira Marcos Aurélio Marques Noronha 《Engineering with Computers》2010,26(1):35-47
Most post-processors for boundary element (BE) analysis use an auxiliary domain mesh to display domain results, working against
the profitable modelling process of a pure boundary discretization. This paper introduces a novel visualization technique
which preserves the basic properties of the boundary element methods. The proposed algorithm does not require any domain discretization
and is based on the direct and automatic identification of isolines. Another critical aspect of the visualization of domain
results in BE analysis is the effort required to evaluate results in interior points. In order to tackle this issue, the present
article also provides a comparison between the performance of two different BE formulations (conventional and hybrid). In
addition, this paper presents an overview of the most common post-processing and visualization techniques in BE analysis,
such as the classical algorithms of scan line and the interpolation over a domain discretization. The results presented herein
show that the proposed algorithm offers a very high performance compared with other visualization procedures. 相似文献