Education for science and science for education: more than a play upon words

In the celebration of the Oswaldo Cruz Institute centenary, we wanted to stress our concern with the relationship between two of its missions: research and education. What are the educational bases required for science and technology activities on health sciences for the future years? How can scientists collaborate to promote the popularization of academic knowledge and to improve a basic education for citizenship in an ethic and humanistic view? In this article we pointed out to need of commitment, even in the biomedical post-graduation level, of a more integrated philosophy that would be centered on health education, assuming health as a dynamic biological and social equilibrium and emphasizing the need of scientific popularization of science in a cooperative construction way, instead of direct transfer of knowledge, preserving also macro views of health problems in the development of very specific studies. The contemporary explosion of knowledge, particularly biological knowledge, imposes a need of continuous education to face the growing illiteracy. In order to face this challenge, we think that the Oswaldo Cruz Institute honors his dialectic profile of tradition and transformation, always creating new perspectives to disseminate scientific culture in innovator forms.     

Na+K+-ATPase Activity and K+ Channels Differently Contribute to Vascular Relaxation in Male and Female Rats

Gender associated differences in vascular reactivity regulation might contribute to the low incidence of cardiovascular disease in women. Cardiovascular protection is suggested to depend on female sex hormones’ effects on endothelial function and vascular tone regulation. We tested the hypothesis that potassium (K⁺) channels and Na⁺K⁺-ATPase may be involved in the gender-based vascular reactivity differences. Aortic rings from female and male rats were used to examine the involvement of K⁺ channels and Na⁺K⁺-ATPase in vascular reactivity. Acetylcholine (ACh)-induced relaxation was analyzed in the presence of L-NAME (100 µM) and the following K⁺ channels blockers: tetraethylammonium (TEA, 2 mM), 4-aminopyridine (4-AP, 5 mM), iberiotoxin (IbTX, 30 nM), apamin (0.5 µM) and charybdotoxin (ChTX, 0.1 µM). The ACh-induced relaxation sensitivity was greater in the female group. After incubation with 4-AP the ACh-dependent relaxation was reduced in both groups. However, the dAUC was greater in males, suggesting that the voltage-dependent K⁺ channel (K_v) participates more in males. Inhibition of the three types of Ca²⁺-activated K⁺ channels induced a greater reduction in R_max in females than in males. The functional activity of the Na⁺K⁺-ATPase was evaluated by KCl-induced relaxation after L-NAME and OUAincubation. OUA reduced K⁺-induced relaxation in female and male groups, however, it was greater in males, suggesting a greater Na⁺K⁺-ATPase functional activity. L-NAME reduced K⁺-induced relaxation only in the female group, suggesting that nitric oxide (NO) participates more in their functional Na⁺K⁺-ATPase activity. These results suggest that the K⁺ channels involved in the gender-based vascular relaxation differences are the large conductance Ca²⁺-activated K⁺ channels (BK_Ca) in females and K_v in males and in the K⁺-induced relaxation and the Na⁺K⁺-ATPase vascular functional activity is greater in males.     

Evolutionary History of the PER3 Variable Number of Tandem Repeats (VNTR): Idiosyncratic Aspect of Primate Molecular Circadian Clock

The PER3 gene is one of the clock genes, which function in the core mammalian molecular circadian system. A variable number of tandem repeats (VNTR) locus in the 18th exon of this gene has been strongly associated to circadian rhythm phenotypes and sleep organization in humans, but it has not been identified in other mammals except primates. To better understand the evolution and the placement of the PER3 VNTR in a phylogenetical context, the present study enlarges the investigation about the presence and the structure of this variable region in a large sample of primate species and other mammals. The analysis of the results has revealed that the PER3 VNTR occurs exclusively in simiiforme primates and that the number of copies of the primitive unit ranges from 2 to 11 across different primate species. Two transposable elements surrounding the 18th exon of PER3 were found in primates with published genome sequences, including the tarsiiforme Tarsius syrichta, which lacks the VNTR. These results suggest that this VNTR may have evolved in a common ancestor of the simiiforme branch and that the evolutionary copy number differentiation of this VNTR may be associated with primate simiiformes sleep and circadian phenotype patterns.     

Evaluation of dental enamel caries assessment using Quantitative Light Induced Fluorescence and Optical Coherence Tomography

An in vitro study of morphological alterations between sound dental structure and artificially induced white spot lesions in human teeth, was performed through the loss of fluorescence by Quantitative Light‐Induced Fluorescence (QLF) and the alterations of the light attenuation coefficient by Optical Coherence Tomography (OCT). To analyze the OCT images using a commercially available system, a special algorithm was applied, whereas the QLF images were analyzed using the software available in the commercial system employed. When analyzing the sound region against white spot lesions region by QLF, a reduction in the fluorescence intensity was observed, whilst an increase of light attenuation by the OCT system occurred. Comparison of the percentage of alteration between optical properties of sound and artificial enamel caries regions showed that OCT processed images through the attenuation of light enhanced the tooth optical alterations more than fluorescence detected by QLF System.

QLF versus OCT imaging of enamel caries: a photonics assessment     

Paleoparasitological remains revealed by seven historic contexts from "Place d'Armes", Namur, Belgium

Human occupation for several centuries was recorded in the archaeological layers of "Place d'Armes", Namur, Belgium. Preventive archaeological excavations were carried out between 1996/1997 and seven historical strata were observed, from Gallo-Roman period up to Modern Times. Soil samples from cesspools, latrines, and structures-like were studied and revealed intestinal parasite eggs in the different archaeological contexts. Ascaris lumbricoides, A. suum, Trichuris trichiura, T. suis. Taenia sp., Fasciola hepatica, Diphyllobothrium sp., Capillaria sp. and Oxyuris equi eggs were found. Paleoparasitology confirmed the use of structures as latrines or cesspit as firstly supposed by the archaeologists. Medieval latrines were not only used for rejection of human excrements. The finding of Ascaris sp. and Trichuris sp. eggs may point to human's or wild swine's feces. Gallo-Roman people used to eat wild boar. Therefore, both A. suum and T. suis, or A. lumbricoides and T. trichuris, may be present, considering a swine carcass recovered into a cesspit. Careful sediment analysis may reveal its origin, although parasites of domestic animals can be found together with those of human's. Taenia sp. eggs identified in latrine samples indicate ingestion of uncooked beef with cysticercoid larvae. F. hepatica eggs suggest the ingestion of raw contaminated vegetables and Diphyllobothrium sp. eggs indicate contaminated fresh-water fish consumption. Ascaris sp. and Trichuris sp. eggs indicate fecal-oral infection by human and/or animal excrements.     

Trypanosoma cruzi: desferrioxamine decreases mortality and parasitemia in infected mice through a trypanostatic effect

Desferrioxamine (DFO) is a potent iron chelator that is also known to modulate inflammation and act as an efficient antioxidant under normal conditions and under oxidative stress. Many in vitro and in vivo studies have shown the efficacy of DFO in the treatment of viral, bacterial and protozoan infections. DFO is known to reduce the intensity of Trypanosoma cruzi infections in mice even during a course of therapy that is not effective in maintaining anaemia or low iron levels. To further clarify these findings, we investigated the action of DFO on mouse T. cruzi infection outcomes and the direct impact of DFO on parasites.Infected animals treated with DFO (5 mg/animal/day) for 35 days, beginning 14 days prior to infection, presented lower parasitemia and lower cumulative mortality rate. No significant effect was observed on iron metabolism markers, erythrograms, leukograms or lymphocyte subsets.In the rapid method for testing in vivo T. cruzi susceptibility, DFO also induced lower parasitemia.In regard to its direct impact on parasites, DFO slightly inhibited the growth of amastigotes and trypomastigotes in fibroblast culture. Trypan blue staining showed no effects of DFO on parasite viability, and only minor apoptosis in trypomastigotes was observed. Nevertheless, a clear decrease in parasite mobility was detected.In conclusion, the beneficial actions of DFO on mice T. cruzi infection seem to be independent of host iron metabolism and free of significant haematological side effects. Through direct action on the parasite, DFO has more effective trypanostatic than trypanocidal properties.