Search Results

You are looking at 1 - 10 of 11 items

  • Author: Ana Batista x
Clear All Modify Search

Abstract

Dysfunctions and dystrophies severely affect the cornea’s function. In point of fact, cornea diseases are the second major cause of blindness worldwide. Corneal diagnosis in clinical practice heavily relies on imaging techniques such as slit lamp microscopy, confocal microscopy, or optical coherence tomography. However, these fail to provide information on the cell’s metabolic state or the structural organization of the corneal stroma. With two-photon microscopy and fluorescence lifetime imaging this information can be obtained. Therefore, corneal pathology diagnosis may be improved. The feasibility of corneal characterization by two-photon imaging has been demonstrated in ex vivo samples and in vivo animal models. In this chapter, we report on the use of two multiphoton microscopy instruments for imaging the human cornea: a 5D multiphoton laser scanning microscope and the multiphoton tomograph MPTflex. Human corneas unsuitable for transplantation but otherwise normal and pathological samples obtained after surgery were imaged and characterized based on their autofluorescence and second-harmonic generation signals. Two possible clinical applications of two-photon microscopy are discussed: (i) the assessment of tissue viability before corneal transplantation and (ii) the differential diagnosis of corneal pathologies, further demonstrating the advantages of this imaging modality for corneal diagnosis.

Abstract

We have recently investigated the long-recognized relationship between complex I and group 4 [NiFe] hydrogenases and we have established the so-called Energy-converting hydrogenase related (Ehr) complex as a new member of the family. We have also observed that four subunits, homologues to NuoB, D, H and L, are common to the members of the family. We have designated this common group of subunits the universal adaptor. Taking into account the similarity of the Na+/H+ antiporter-like subunits of complex I (NuoL, NuoM and NuoN) and the unique structural characteristic of the long amphipathic α helix part of NuoL, the nature of the antiporter-like subunit of the universal adaptor was questioned. Thus, in this work we further explore the properties of the universal adaptor, investigating which antiporter-like subunit is part of the universal adaptor. We observe that the universal adaptor contains an antiporter-like subunit with a long amphipathic α helix, similar to NuoL. Consequently, the long helix is a common denominator that has been conserved in all members of the family. Such conservation surely reflects the key role of such helix in the energy transduction mechanism of this family of enzymes.

Abstract

One of the main processes within the additive manufacturing is fused deposition modeling, due to its versatility, its high capacities, and its low cost. However, this process has certain restrictions that enhance its expansion in the industrial sector such as porosity in the structure and reduced surface quality, in addition to the anisotropy generated by the trajectories and deposition of the layers. Also the current trend in the world is to reduce the consumption of petroleum-based polymers, so alternatives must be found in biodegradable materials to move the process toward an ecosustainable industry. Therefore, this chapter compiles an introduction to the state of the art of this technology of such potential with the use of a biodegradable polymer, polylactic acid. It considers the characteristic defectology of this process, the main parameters, as well as the possible applications in which it is implanted and in which it could be implanted. Finally, different possibilities are considered for improving the surface quality of the parts generated with this technology by means of different types of post-processing

Abstract

The ability of polar (1:1 water/methanol) and non-polar (dichloromethane) extracts of macroalgae from Arraial do Cabo, RJ, Brazil, to inhibit quorum sensing (QS) was investigated. Before extraction, half of the algae were treated with 30% ethanol to kill and remove surface-associated bacteria. Twenty of 22 polar extracts inhibited the QS of the acyl homoserine lactone (AHL) producer and reporter Chromobacterium violaceum CV017 with minimal inhibitory concentrations (MIC) ranging from 0.28 μg ml-1 (Ulva fasciata) to 189 μg ml-1 (Codium sp.). The MIC of non-polar extracts varied from 69 μg ml-1 (Sargassum furcatum) to 2730 μg ml-1 (Peyssonnelia capensis). Usually, extracts from algae with associated bacteria had a higher bioactivity than ones without them. Among 11 algal species tested, 50% of extracts with associated bacteria were toxic to C. violaceum CV026. None of the extracts contained AHLs, which was shown using reporters C. violaceum CV026 and Agrobacterium tumefaciens NTL4 (pZLR4). Polar (11%) and non-polar extracts (2%) inhibited QS-dependent attachment of Pseudomonas aeruginosa PA01 at tissue-level concentrations. Our data suggest that secondary metabolites from algae and their associated microbiota are an important source of QS inhibitors, which potentially can be used in future biotechnological applications.

Six mexicanolide limonoids isolated from the dichloromethane extract of the fruits of Cipadessa fruticosa Blume (Meliaceae) were evaluated against Spodoptera frugiperda (J. E. Smith). Gedunin was used as a positive control. When incorporated into an artificial diet of neonates at 50.0 mg kg-1, febrifugin A showed 73.3% mortality. All the compounds showed moderate insecticidal activity, except for ruageanin A, when compared with the control. Febrifugin also showed growth inhibition and antifeedant activities (at 100.0 mg kg-1). The correlation between the insecticidal activity of the isolated compounds and their chemical structure was discussed.

Phenolic compounds are found in seaweed species together with other substances presenting antioxidant activity. The objective of this work was to evaluate the antioxidant activity of the free phenolic acids (FPA) fraction from the seaweed Halimeda monile, and its activity to protect the expression of hepatic enzymes in rats, under experimental CCl4 injury. The antioxidant activity was measured by the DPPH method. The FPA fraction (80 mg/kg, p.o.) was administered during 20 consecutive days to rats. The peroxidation was performed by thiobarbituric acid reactive substances (TBARS). The SOD and CAT enzymatic expressions were measured by RT/PCR. The histology technique was used to evaluate liver injuries. The expression of both, CAT and SOD genes, was more preserved by FPA. Only partial injury could be observed by histology in the liver of rats receiving FPA as compared with the control group; and CCl4 administration induced 60% more peroxidation as compared with the rats receiving FPA. These data suggest that FPA could modulate the antioxidant enzymes and oxidative status in the liver through protection against adverse effects induced by chemical agents

This work describes the ability of living Trichomonas vaginalis to hydrolyze extracellular ATP (164.0 ± 13.9 nmol Pi / h × 107 cells). This ecto-enzyme was stimulated by ZnCl2, CaCl2 and MgCl2, was insensitive to several ATPase and phosphatase inhibitors and was able to hydrolyze several nucleotides besides ATP. The activity was linear with cell density and with time for at least 60 min. The optimum pH for the T. vaginalis ecto-ATPase lies in the alkaline range. ᴅ-galactose, known to be involved in adhesion of T. vaginalis to host cells, stimulated this enzyme by more than 90%. A comparison between two strains of T. vaginalis showed that the ecto-ATPase activity of a fresh isolate was twice as much as that of a strain axenically maintained in culture, through daily passages, for several years. The results suggest a possible role for this ecto-ATPase in adhesion of T. vaginalis to host cells and in its pathogenicity.

Termites have become an important pest of Eucalyptus and Pinus reforestations, sugarcane and other cultures. An alternative for the control of this pest would be the use of attractive traps that take in account the social behavior of these insects. Diverse factors are important for the insects in the localization of the habitat and the choice of the food and specific odors can facilitate this. Studies referring to Heterotermes tenuis (Isoptera: Rhinotermitidae) are scarce. The objective of this work was to analyze the tergal cuticular extract of H. tenuis and determine the selectivity and sensitivity of its antennae to the components of this extract by electroantennography (EAG). The composition of the cuticular extract was determined by GC-MS analysis. The hydrocarbons found were restricted to linear alkanes, being most abundant C24 to C27 that comprises ca. 65% of the total. Olefins were not detected. EAG and behavioral test responses to the cuticular hydrocarbons were greater and significantly different from the control and the high selectivity of the antennae to the extract indicates its potential as chemical messenger. Cuticular hydrocarbons mixture is species-specific and can be used to identify a given taxon without the diagnostic castes, soldiers or imagoes. Difference in the composition appears to relate with the type of habitat of specie.

Abstract

Background

Running economy (RE), expresses the relationship between the energy cost of running (Cr) and the work performed by a runner and is an predictor of performance. Given the intense effort of marathon runners during training and competition and the dearth of studies that address performance and cytokines in this population, the objective of the current study was to investigate the relationship between RE and cytokines in marathon runners.

Methods

A total of 22 recreational marathon runners were examined. Using data obtained from VO2max assessments and sub-maximal tests, the following formula was applied to determine RE: Cr (mLO2·kg-1·km-1) = VO2 (mL·kg-1·h-1) × 60 ÷ speed (km·h-1).

Results

Cr values shows no correlation with levels of the serum IL-1β, IL-4, IL-8, IL-10 and TNF-a 24h before, immediately after or 72h after the completion of an official marathon. However, the IL-6 level shows a significant correlation with Cr.

Discussion and conclusion

The relationship between higher values of IL-6 and lower RE leads to the hypothesis of a physical under-recovery state by some athletes. Considering the stress caused by training, associated with the higher energetic cost in less economic athletes, it’s possible that the period of resting may not totally compensate for the inflammatory state.

Abstract

Introduction:

The changes in the eating habits associated with physical inactivity are directly related to the increase in the prevalence of obesity and associated diseases such as diabetes mellitus (DM), metabolic syndrome and cardiovascular diseases.

Objective:

The aim of this study was to investigate the relationship between the frequency of consumption of some food groups (snacks, fruits, vegetables and candies), physical exercise, nutritional classification and biochemical profile in children.

Methods:

After the approval of the Ethics Committee, we studied 882 schoolchildren ranging between 6 and 10 years of age. Biochemical and anthropometric evaluations were performed and questionnaires were used in order to check the eating habits and physical activity.

Results:

Our results showed that we may relate the consumption of snacks, fruits, vegetables or candies with modifications in the glycemia, triglycerides, total cholesterol, HDL-c, and LDL-c but we did not observe association with the nutritional classification. It is noteworthy to say that almost 50% of the studied children were overweight or obese and many presented alterations in the lipid and glucose levels.

Conclusion:

Our results also show that many children have abnormal levels of lipids and glycemia and a great number of them are classified as overweight or obese. In this context, we can say that urgent approaches are needed to be carried out by a multidisciplinary team in order to improve the diet and reduces the risk factors in this population of children and prevent secondary diseases in adolescence and adulthood.