A method for testing the host specificity of ectoparasites: give them the opportunity to choose

Host-choice experiments were carried out with rodent and bat ectoparasites on Ilha Grande, state of Rio de Janeiro, Brazil. We constructed experimental chambers that enclosed three different rodent or bat host species, and then introduced a selected set of ectoparasitic arthropods. When given the opportunity to choose among host species, the ectoparasites showed a strong tendency to select their primary hosts, and reject novel host species. These kinds of simple experiments can be valuable tools for assessing the ability of ectoparasites to locate and discern differences between host species, and make choices about which hosts to infest, and which hosts to avoid.

Effect of training on the ability of dual-task coordination

Within the framework of the working memory model proposed by A. Baddeley and G. Hitch, a dual-task paradigm has been suggested to evaluate the capacity to perform simultaneously two concurrent tasks. This capacity is assumed to reflect the functioning of the central executive component, which appears to be impaired in patients with dysexecutive syndrome. The present study extends the investigation of an index ("mu"), which is supposed to indicate the capacity of coordination of concurrent auditory digit span and tracking tasks, by testing the influence of training on the performance in the dual task. The presentation of the same digit sequence lists or always-different lists did not differently affect the performance. The span length affected the mu values. The improved performance in the tasks under the dual condition closely resembled the improvement in the single-task performance. So, although training improved performance in the single and dual conditions, especially for the tracking component, the mu values remained stable throughout the sessions when the single tasks were performed first. Conversely, training improved the capacity of dual-task coordination throughout the sessions when dual task was performed first, addressing the issue of the contribution of the within-session practice to the mu index.

An MD-PhD program in Brazil: students’ concepts of science and of common sense

In 1995, a pioneering MD-PhD program was initiated in Brazil for the training of medical scientists in experimental sciences at the Federal University of Rio de Janeiro. The program’s aim was achieved with respect to publication of theses in the form of papers with international visibility and also in terms of fostering the scientific careers of the graduates. The expansion of this type of program is one of the strategies for improving the preparation of biomedical researchers in Brazil. A noteworthy absence of interest in carrying out clinical research limits the ability of young Brazilian physicians to solve biomedical problems. To understand the students’ views of science, we used qualitative and quantitative triangulation methods, as well as participant observation to evaluate the students’ concepts of science and common sense. Subjective aspects were clearly less evident in their concepts of science. There was a strong concern about "methodology", "truth" and "usefulness". "Intuition", "creativity" and "curiosity" were the least mentioned thematic categories. Students recognized the value of intuition when it appeared as an explicit option but they did not refer to it spontaneously. Common sense was associated with "consensus", "opinion" and ideas that "require scientific validation". Such observations indicate that MD-PhD students share with their senior academic colleagues the same reluctance to consider common sense as a valid adjunct for the solution of scientific problems. Overcoming this difficulty may be an important step toward stimulating the interest of physicians in pursuing experimental research.

Rheology of spreadable goat cheese made with autochthonous lactic cultures differing in their ability to produce exopolysaccharides

The aim of this study was to compare the rheology of spreadable cheeses elaborated with autochthonous lactic starter cultures without the addition of exopolysaccharide-producing strain in the same starter with exopolysaccharide-producing strain. From a rheological standpoint, both samples were characterized as weak viscoelastic gels and pseudoplastic products. It was concluded that cheese made with exopolysaccharide-producing strain showed smaller G', G", and η* values over the range of frequencies studied and smaller critic stress values than the cheese without exopolysaccharide-producing strain. The results obtained indicate that cheeses without exopolysaccharide-producing strain need to be added with any texture enhancer product.

Ability of a Lactobacillus rhamnosus strain cultured in milk whey based medium to bind aflatoxin B1

This study aimed to compare Lactobacillus rhamnosus growth in MRS (de Man, Rogosa and Sharpe) broth and a culture medium containing milk whey (MMW) and to evaluate aflatoxin B1 (AFB1) adsorption capacity by bacterial cells produced in both culture media. L. rhamnosus cells were cultivated in MRS broth and MMW (37 °C, 24 hours), and bacterial cell concentration was determined spectrophotometrically at 600 nm. AFB1 (1 µg/ml) adsorption assays were conducted using 1 x 10(10) non-viable L. rhamnosus cells (121 °C, 15 minutes) at pHs 3.0 and 6.0 and contact time of 60 minutes. AFB1 quantification was performed by High Performance Liquid Chromatography. Bacterial cell concentration in MMW was higher (9.84 log CFU/ml) than that in MRS broth (9.63 log CFU/ml). There were no significant differences between AFB1 binding results at the same pH value (3.0 or 6.0) for the cells cultivated in MRS broth (46.0% and 35.8%, respectively) and in MMW (43.7% and 25.8%, respectively), showing that MMW can adequately replace the MRS broth. Therefore, it can be concluded that the use of L. rhamnosus cells cultivated in MMW offers advantages such as reduction in large scale production costs, improvement of environmental sustainability, and being a practicable alternative for decontamination of food products susceptible to aflatoxin contamination.