Life & Health Sciences

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Permeation of probe molecules into alginate microbeads: Effect of salt and processing


ABSTRACT

The ability to exclude harmful factors from a hydrogel microbead is important for the degree of protection the beads offers to what is encapsulated within. The permeability of alginate microbeads, prepared by water-in-oil emulsification, was investigated by their ability to exclude FITC-labelled protein probes. The influence of alginate concentration, calcium concentration and method of addition, and salt content of the environment was investigated. The permeability was also compared to the permeability of beads made by the traditional method of dripping an alginate solution into a CaCl2 solution. Beads produced with low amounts of CaCl2 show a significant degree of swelling and are therefore very permeable (C/C0 (BSA) = 0.62, where C is the final concentration of BSA-FITC in the bead, and C0 the concentration of BSA-FITC in the continuous phase). With additional calcium, either by adding more calcium crystals after the emulsification step or by washing with a CaCl2 solution, beads swell less and are less permeable (C/C0 (BSA) = 0.13 and 0.12). Beads made by dripping are very permeable (C/C0 (BSA) ∼ 0.60). Because in this process the droplets of alginate are not constrained by a water-oil boundary, the beads can swell during gelation. The salt concentration in the continuous phase influences the strength of the electrostatic repulsion between the probes and the alginate network and hence affects the permeation of the probes into the beads. In the absence of salt, even FITC (389Da) is mostly excluded from the interior of the beads (C/C0 (FITC) ∼ 0.09).


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Species-specific patterns of shelter exploitation in Chagas disease vectors of the genus Rhodnius


ABSTRACT

Triatomines are insect vectors of Trypanosoma cruzi¸ the etiological agent of Chagas disease. Several species belonging to the genus Rhodnius (Hemiptera: Reduviidae) have been reported inhabiting domestic and peridomestic environments in different regions of Latin America. However, behavioral and sensory ecology aspects related to their use of shelters have been poorly studied. The objective of the present study was to characterize how bug density, illumination and thigmotactic information affect the use of shelters by three species belonging to the Rhodnius prolixus species complex. We evaluated whether exposure to different insect densities affects the proportion of R. prolixus, Rhodnius robustus and Rhodnius neglectus that choose to stay inside a refuge. Besides, we evaluated whether absence of an illumination regime affects their tendency to hide in shelters. Our results showed that the proportion of individuals that remained outside the shelter increased with rising insect densities. Nevertheless, while R. prolixus only reacted by augmenting this proportion with the highest density tested, the other species showed significant increases already at lower densities. On the other hand, a significantly higher number of R. robustus stayed outside the shelter in the absence of a light cycle, while no change was induced for the other species. Thus, this study determined species-specific profiles of refuge exploitation defined by factors such as thigmotaxis and negative phototaxis. The differences observed among these Rhodnius species may impact their house colonization abilities, which seem to be critically affected by bug hiding performance during health service detection processes.


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Attraction of Rhodnius prolixus males to a synthetic female-pheromone blend


ABSTRACT

Background
The triatomine bug Rhodnius prolixus Stål, 1859 (Heteroptera: Reduviidae) is the primary vector of Chagas disease in Colombia and Venezuela. An important step in controlling Chagas disease is monitoring the growth and spread of bug populations to inform effective management. Such monitoring could be carried out using pheromone traps. To develop effective pheromone traps, it is vital to understand the pheromone chemistry of R. prolixus. Previous studies have found that female R. prolixus metasternal gland secretions induce males to: leave shelters, take off, orientate during walking, aggregate around mating pairs, and mate. This study aims to identify a synthetic blend of female metasternal gland compounds that could be used to attract R. prolixus.

Results
We investigated the electrophysiological activity of the ten most abundant compounds in female R. prolixus metasternal glands using single sensillum recordings. In total we obtained 60 recordings from basiconic sensilla in male R. prolixus. In 31 of these recordings, responses to individual compounds were observed. Each of the ten tested compounds elicited neuron responses in a minimum of eight recordings. Having confirmed their electrophysiological activity, we tested these ten compounds by presenting them to male Rhodnius prolixus in a “T” olfactometer. Male bugs showed a significant preference for the blend of metasternal gland compounds compared to the clean air control.

Conclusions
A simple blend of ten compounds found in female R. prolixus metasternal glands is attractive to conspecific males. All compounds in the blend are either commercially available at low cost, or easily synthetically prepared from simple precursors. We hope that this blend will be evaluated as a lure for pheromone traps in field bioassays.


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Co-existing locomotory activity and gene expression profiles in a kissing-bug vector of Chagas disease


ABSTRACT

The triatomine bug Rhodnius prolixus is a main vector of Chagas disease, which affects several million people in Latin-America. These nocturnal insects spend most of their locomotory activity during the first hours of the scotophase searching for suitable hosts. In this study we used multivariate analysis to characterize spontaneous locomotory activity profiles presented by 5th instar nymphs. In addition, we investigated whether sex and the expression of the foraging (Rpfor) gene could modulate this behavioral trait. Hierarchical Clustering and Redundancy Analyses detected individuals with distinct locomotory profiles. In addition to a great variation in locomotory intensity, we found that a proportion of nymphs walked during unusual time intervals. Locomotory activity profiles were mostly affected by the cumulative activity expressed by the nymphs. These effects promoted by cumulative activity were in turn influenced by nymph sex. Sex and the Rpfor expression had a significant influence on the profiles, as well as in the levels of total activity. In conclusion, the locomotory profiles evinced by the multivariate analyses suggest the co-existence of different foraging strategies in bugs. Additionally, we report sex-specific effects on the locomotion patterns of 5th instar R. prolixus, which are apparently modulated by the differential expression of the Rpfor gene.


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Activity and shelter-related behavior in Rhodnius prolixus: The role of host odours


ABSTRACT

Triatomine bugs are considered nocturnal insects that feed on the blood of vertebrates and remain hidden inside narrow shelters during daylight hours. Nevertheless, it is not clear whether these insects become active and leave their shelters on a daily basis, less frequently or, even fortnightly. Activity patterns were studied in Rhodnius prolixus Stål, 1859 (Hemiptera: Triatominae) associated with shelters to evaluate whether the decision to leave a shelter depends on bug starvation and the presence of host odours. Experiments were conducted with groups of 5th instar nymphs released in an experimental arena offering an artificial shelter consisting of a piece of corrugated cardboard positioned in its centre. Results indicate that host odours promoted a significant increase in shelter related activity, i.e. shelter-leaving or entering movements, and also in bug locomotion. This increase could only be observed with bugs starved for 30 or 60 days, but not for 21 days. Most R. prolixus nymphs that left shelters and engaged in locomotory activity were starved and in the presence of host odours. Even though R. prolixus is mostly considered a very active and “aggressive” triatomine, our results contradict this perspective and suggest that its main strategy regarding hosts is to wait and carefully evaluate feeding chances before becoming exposed. This behavioural strategy might have arisen through their evolution in palm trees in association with a diverse fauna that may impose predation risks.


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Molecular bases of sensory processes in kissing bugs, vectors of Chagas disease


ABSTRACT

Sensory processes represent an information gathering interface between animals and their surrounding world. Therefore, they serve to scan the environment for resources and threats. The behavior of kissing bugs has been studied to aid their control because they transmit Chagas disease to humans. Besides, a few triatomines represent important insect models since Wigglesworth times. These hematophagous insects rely on different sensory systems to scan their environment for blood-sources, mating partners and hiding places. The study of the molecular bases of sensory processes has undergone a dramatic progress due the advent of new technologies allowing mass-sequencing of genes. Here we focus on reviewing the fundamental knowledge gathered to date about the molecular bases of kissing bug sensory processes.


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A novel 3D nanofibre scaffold conserves the plasticity of glioblastoma stem cell invasion by regulating galectin-3 and integrin-β1 expression


ABSTRACT

Glioblastoma Multiforme (GBM) invasiveness renders complete surgical resection impossible and highly invasive Glioblastoma Initiating Cells (GICs) are responsible for tumour recurrence. Their dissemination occurs along pre-existing fibrillary brain structures comprising the aligned myelinated fibres of the corpus callosum (CC) and the laminin (LN)-rich basal lamina of blood vessels. The extracellular matrix (ECM) of these environments regulates GIC migration, but the underlying mechanisms remain largely unknown. In order to recapitulate the composition and the topographic properties of the cerebral ECM in the migration of GICs, we have set up a new aligned polyacrylonitrile (PAN)-derived nanofiber (NF) scaffold. This system is suitable for drug screening as well as discrimination of the migration potential of different glioblastoma stem cells. Functionalisation with LN increases the spatial anisotropy of migration and modulates its mode from collective to single cell migration. Mechanistically, equally similar to what has been observed for mesenchyma I migration of GBM in vivo, is the upregulation of galectin-3 and integrin-beta 1 in Gli4 cells migrating on our NF scaffold. Downregulation of Calpain-2 in GICs migrating in vivo along the CC and in vitro on LN-coated NF underlines a difference in the turnover of focal adhesion (FA) molecules between single-cell and collective types of migration.


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Inpatient trunk exercises after recent stroke: an update meta-analysis of randomized controlled trials.


ABSTRACT

INTRODUCTION:Although the role of trunk exercises in the chronic phase of stroke is acknowledged, the addition of specific inpatient training in the subacute stage is a matter of debate and varies among centers. Recent new evidence suggests the question should be revisited. OBJECTIVE:To assess the impact of the addition of specific trunk training to inpatient rehabilitation protocols after a recent stroke. METHODS:A systematic review was performed assessing the impact of inpatient trunk training. The search was performed in LILACS, SciELO, PEDro, Cochrane, and NCBI PubMed databases for clinical trials published up to December 31st, 2017. The initial bibliographic research identified 3202 articles. After analyzing the titles, 19 abstracts were selected for detailed analysis. After application of the eligibility criteria, the final selection included nine studies. Outcome measurements from the same evaluation instruments were submitted to a meta-analysis to improve homogeneity (7 studies). RESULTS:All patients in the included studies were recruited less than three months after a stroke. Seven studies assessed trunk control using the Trunk Impairment Scale (TIS). There was a significant improvement in trunk control with a pooled increase in TIS score of 3.3 points from the baseline (CI95:2.54–4.06, p 


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Stereoscopic images from computed tomography angiograms


ABSTRACT

Objective
To present an adaptation of the anaglyph photography technique to be used with radiological images from computed tomography angiograms, enabling stereoscopic visualization of a patient's individual abnormal vascular anatomy for teaching, case discussion, or surgical planning purposes.

Methods
Traditional anaglyph procedures with actual objects yield 2 independent photographs, simulating the image perceived by each eye. Production of anaglyphs from angiograms involve 3 basic procedures: volume rendering, image capture, and image fusion. Volume renderings were reconstructed using a free, open-source DICOM (Digital Imaging and Communications in Medicine) reader. Subsequently, the virtual object was positioned to mimic the operator's angle of view, and different perspectives of the reconstructed volume could be obtained through exclusively horizontal rotation. The 2 images were then fused after their color composition was modified so that each eye would perceive only 1 image when using anaglyph glasses.

Results
Forty-three angiograms were reviewed for the purpose of this study and a total of 6 examinations were selected for illustration of the technique. Stereoscopic display was possible for all of them and in the 3 types of support tested: computer monitor, tablet, and smartphone screens.

Conclusions
Anaglyph display of computed tomography angiograms is an effective and low-cost alternative for the stereoscopic visualization of a patient's individual intracranial vascular anatomy.


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Combining proprioceptive neuromuscular facilitation and virtual reality for improving sensorimotor function in stroke survivors: a randomized clinical trial


ABSTRACT

Aim of the study: To assess a program combining virtual reality (VR) games and proprioceptive neuromuscular facilitation (PNF), and to compare it to the standalone techniques in stroke survivors.
Methods: A randomized controlled clinical trial. Forty-eight participants were recruited in the outpatient clinic of a University Hospital in Salvador, Brazil. They were randomly assigned to three groups (n=16 each): PNF, VR, and PNF/VR. Participants attended twice-weekly fifty-minute sessions over a two-month period. The PNF/VR group performed both PNF and virtual reality exercises employing Nintendo Wii electronic games. Motor performance was assessed before and immediately after the treatment using the Fugl-Meyer Assessment scale.
Results: Improvement in the mean scores was observed after treatment independent of the allocation group with significant intra-group changes: 14.5, 10.5, and 10.4 for PNF, VR and PNF/VR, respectively. Score changes were also observed in the analyses of specific sections as follows: (1) A significant improvement in the passive movement and pain score was observed in the PNF and PNF/VR groups. (2) The same was observed for the motor function of the upper limb in all groups, for the motor function of the lower limb in the VR group and for balance in the PNF and PNF/VR groups.
Conclusion: The use of a program combining virtual rehabilitation and PNF presented results that were comparable to those obtained with the isolated techniques