Learning through role-playing games: an approach for active learning and teaching

This study evaluates the use of role-playing games (RPGs) as a methodological approach for teaching cellular biology, assessing student satisfaction, learning outcomes, and retention of acquired knowledge. First-year undergraduate medical students at two Brazilian public universities attended either an RPG-based class (RPG group) or a lecture (lecture-based group) on topics related to cellular biology. Pre- and post-RPG-based class questionnaires were compared to scores in regular exams and in an unannounced test one year later to assess students' attitudes and learning. From the 230 students that attended the RPG classes, 78.4% responded that the RPG-based classes were an effective tool for learning; 55.4% thought that such classes were better than lectures but did not replace them; and 81% responded that they would use this method. The lecture-based group achieved a higher grade in 1 of 14 regular exam questions. In the medium-term evaluation (one year later), the RPG group scored higher in 2 of 12 questions. RPG classes are thus quantitatively as effective as formal lectures, are well accepted by students, and may serve as educational tools, giving students the chance to learn actively and potentially retain the acquired knowledge more efficiently.

The use and mis-use of some ecological terms and concepts in epidemiology

The article discusses the current use and mis-use of ecological terms and concepts in epidemiological literature, and in special, in works dealing with zoonotic diseases. A selection of examples was taken from papers recently published on the transmission of Chagas' disease by Triatoma sordida. Proper definitions are listed, with the intent of helping non-ecologists to use those terms and concepts correctly.

General terms and rigidity: another solution to the trivialization problem

In this paper I am concerned with the problem of applying the notion of rigidity to general terms. In Naming and Necessity, Kripke has clearly suggested that we should include some general terms among the rigid ones, namely, those common nouns semantically correlated with natural substances, species and phenomena, in general, natural kinds -'water', 'tiger', 'heat'- and some adjectives -'red', 'hot', 'loud'. However, the notion of rigidity has been defined for singular terms; after all, the notion that Kripke has provided us with is the notion of a rigid designator. But general terms do not designate single individuals: rather, they apply to many of them. In sum, the original concept of rigidity cannot be straightforwardly applied to general terms: it has to be somehow redefined in order to make it cover them. As is known, two main positions have been put forward to accomplish that task: the identity of designation conception, according to which a rigid general term is one that designates the same property or kind in all possible worlds, and the essentialist conception, which conceives of a rigid general term as an essentialist one, namely, a term that expresses an essential property of an object. My purpose in the present paper is to defend a particular version of the identity of designation conception: on the proposed approach, a rigid general term will be one that expresses the same property in all possible worlds and names the property it expresses. In my opinion, the position can be established on the basis of an inference to the best explanation of our intuitive interpretation and evaluation, relative to counterfactual circumstances, of statements containing different kinds of general terms, which is strictly analogous to our intuitive interpretation and evaluation, relative to such circumstances, of statements containing different kinds of singular ones. I will argue that it is possible to offer a new solution to the trivialization problem that is thought to threaten all versions of the identity of designation conception of rigidity. Finally, I will also sketch a solution to the so-called 'over-generalization and under-generalization problems', both closely related to the above-mentioned one.

Prevalence of alcohol and tobacco use among Brazilian adolescents: a systematic review

OBJECTIVE: To analyze alcohol and tobacco use among Brazilian adolescents and identify higher-risk subgroups. METHODS: A systematic review of the literature was conducted. Searches were performed using four databases (LILACS, MEDLINE /PubMed, Web of Science, and Google Scholar), specialized websites and the references cited in retrieved articles. The search was done in English and Portuguese and there was no limit on the year of publication (up to June 2011). From the search, 59 studies met all the inclusion criteria: to involve Brazilian adolescents aged 10-19 years; to assess the prevalence of alcohol and/or tobacco use; to use questionnaires or structured interviews to measure the variables of interest; and to be a school or population-based study that used methodological procedures to ensure representativeness of the target population (i.e. random sampling). RESULTS: The prevalence of current alcohol use (at the time of the investigation or in the previous month) ranged from 23.0% to 67.7%. The mean prevalence was 34.9% (reflecting the central trend of the estimates found in the studies). The prevalence of current tobacco use ranged from 2.4% to 22.0%, and the mean prevalence was 9.3%. A large proportion of the studies estimated prevalences of frequent alcohol use (66.7%) and heavy alcohol use (36.8%) of more than 10%. However, most studies found prevalences of frequent and heavy tobacco use of less than 10%. The Brazilian literature has highlighted that environmental factors (religiosity, working conditions, and substance use among family and friends) and psychosocial factors (such as conflicts with parents and feelings of negativeness and loneliness) are associated with the tobacco and alcohol use among adolescents. CONCLUSIONS: The results suggest that consumption of alcohol and tobacco among adolescents has reached alarming prevalences in various localities in Brazil. Since unhealthy behavior tends to continue from adolescence into adulthood, public policies aimed towards reducing alcohol and tobacco use among Brazilians over the medium and long terms may direct young people and the subgroups at higher risk towards such behavior.

Comparative study of the biological behaviour in hamster of two isolates of leishmania characterized respectively as L. major-like and L. donovani

Hamster inoculated intraperitoneally with 1 x 10(7) parasites of L. donovani and L. major-like of the New World were studied in groups of 15, 30, 60 and 90 days of infection. The parasite load and density showed progressive increase with the evolution of the infection and was higher in the L. donovani groups than in the L. major-like groups. The L. major-like groups showed parasite density higher in the spleen than in the liver and was similar in both organs in L. donovani groups. The histopathology showed a diffuse marked hyperplasia and hypertrophy of the reticuloendothelial system with high parasitism in the L. donovani groups while there was focal involvement of these organs in L. major-like groups, forming nodules of macrophages that were scantly parasitised. The biological behaviour could be useful in the preliminary studies of Leishmania strain in regional laboratories and understanding the histopathology of lesions caused by different leishmania species.

The Bambuí health and aging study (BHAS). Prevalence of intermittent claudication in the aged population of the community of Bambuí and its associated factors

OBJECTIVE: To assess the prevalence of intermittent claudication in the aged population of Bambuí, Brazil, and to identify the factors associated with this disease. METHODS: Population-based cross-sectional study of the aged population ( > or = 60 years of age) of Bambuí. Participants were interviewed and examined, after written consent. Intermittent claudication was defined based on a standardized questionnaire. Analysis was performed using multiple logistic regression. RESULTS: Of the 1,742 elderly living in Bambuí, 1,485 (85.2%) were enrolled in the study. Thirty-seven individuals (2.5%) with intermittent claudication were identified: 28 (1.9%) males and 9 (0.6%) females. Their age brackets were: 16 (1.08%) individuals between 60 and 69 years of age, 17 (1.15%) between 70 and 79 years, and 4 (0.27%) > or = 80 years. A significant association between intermittent claudication and the following characteristics was found: male sex (OR=5.1; CI 2.4-11.0), smokers (OR=3.1; CI 1.2-8.5), ex-smokers (OR=3.4; CI 1.3-8.7), and more than 2 hospital admissions in the last 12 months (OR=2.8; CI 1.1-7.2). CONCLUSION: Disease prevalence was similar to that of other countries. The association between intermittent claudication and smoking strengthens the significance of tobacco in peripheral artery disease pathogenesis. The association of intermittent claudication and a higher number of hospital admissions suggests greater morbidity in the elderly affected.

Nephrotoxicity Of Polymyxin B: Experimental Study In Cells And Implications For Nursing Practice

The aim of the study was to characterize the cell damage mechanisms involved in the pathophysiology of cytotoxicity of polymyxin B in proximal tubular cells (LLC - PK1) and discuss about the nurses interventions to identify at risk patients and consider prevention or treatment of nephrotoxicity acute kidney injury. This is a quantitative experimental in vitro study, in which the cells were exposed to 375μM polymyxin B sulfate concentration. Cell viability was determined by exclusion of fluorescent dyes and morphological method with visualization of apoptotic bodies for fluorescence microscopy. Cells exposed to polymyxin B showed reduced viability, increased number of apoptotic cells and a higher concentration of the enzyme lactate dehydrogenase. The administration of polymyxin B in vitro showed the need for actions to minimize adverse effects such as nephrotoxicity.


Study of the effects of ß-myrcene on rat fertility and general reproductive performance

ß-Myrcene (MYR) is a monoterpene found in the oils of a variety of aromatic plants including lemongrass, verbena, hop, bay, and others. MYR and essential oils containing this terpenoid compound are used in cosmetics, household products, and as flavoring food additives. This study was undertaken to investigate the effects of MYR on fertility and general reproductive performance in the rat. MYR (0, 100, 300 and 500 mg/kg) in peanut oil was given by gavage to male Wistar rats (15 per dose group) for 91 days prior to mating and during the mating period, as well as to females (45 per dose group) continuously for 21 days before mating, during mating and pregnancy, and throughout the period of lactation up to postnatal day 21. On day 21 of pregnancy one-third of the females of each group were submitted to cesarean section. Resorption, implantation, as well as dead and live fetuses were counted. All fetuses were examined for external malformations, weighed, and cleared and stained with Alizarin Red S for skeleton evaluation. The remaining dams were allowed to give birth to their offspring. The progeny was examined at birth and subsequently up to postnatal day 21. Mortality, weight gain and physical signs of postnatal development were evaluated. Except for an increase in liver and kidney weights, no other sign of toxicity was noted in male and female rats exposed to MYR. MYR did not affect the mating index (proportion of females impregnated by males) or the pregnancy index (ratio of pregnant to sperm-positive females). No sign of maternal toxicity and no increase in externally visible malformations were observed at any dose level. Only at the highest dose tested (500 mg/kg) did MYR induce an increase in the resorption rate and a higher frequency of fetal skeleton anomalies. No adverse effect of MYR on postnatal weight gain was noted but days of appearance of primary coat, incisor eruption and eye opening were slightly delayed in the exposed offspring. On the basis of the data presented in this paper the no-observed-adverse-effect level (NOAEL) for toxic effects on fertility and general reproductive performance can be set at 300 mg of ß-myrcene/kg body weight by the oral route.

Comparative study of IgA nephropathy with and without crescents

Glomerular crescents were analyzed as a prognostic factor in retrospectively reviewed data from 144 patients with biopsy-proven IgA nephropathy. Crescents were found in 26 (18%) patients, and detected in 2 to 100% of glomeruli in each specimen. In 5% of the patients more than 50% of the glomeruli were affected. Thirty patients with IgA nephropathy without crescents were studied as a control group. Mean age was 30.3 ± 9.4 and 30.2 ± 12.0 years for the patients with and without crescents, respectively, and males prevailed in both groups. The length of follow-up was 23.2 ± 41.6 months for patients with crescents and 29.3 ± 35.3 months for patients without crescents. Eighty percent of the patients with crescents were hypertensive, compared to 27% of the non-crescent control group (P < 0.05). Mean serum creatinine at the time of diagnosis was 3.9 ± 2.9 and 1.9 ± 2.1 mg/dl for the patients with and without crescents, respectively. Initial urinary protein excretion was higher in patients with crescents (4.6 ± 3.5 vs 1.2 ± 0.9 g/day; P < 0.05). At the end of follow-up 17 patients (77.3%) from the crescent group and 3 (11.1%) from the non-crescent group had end-stage renal disease (P < 0.0001). The presence of crescents was associated with higher levels of initial serum creatinine and urinary protein excretion, and a higher frequency of hypertension and progression to end-stage renal disease.

Co-culture of chondrocytes and bone marrow mesenchymal stem cells in vitro enhances the expression of cartilaginous extracellular matrix components

Chondrocytes and bone marrow mesenchymal stem cells (BMSCs) are frequently used as seed cells in cartilage tissue engineering. In the present study, we determined if the co-culture of rabbit articular chondrocytes and BMSCs in vitro promotes the expression of cartilaginous extracellular matrix and, if so, what is the optimal ratio of the two cell types. Cultures of rabbit articular chondrocytes and BMSCs were expanded in vitro and then cultured individually or at a chondrocyte:BMSC ratio of 4:1, 2:1, 1:1, 1:2, 1:4 for 21 days and cultured in DMEM/F12. BMSCs were cultured in chondrogenic induction medium. Quantitative real-time RT-PCR and Western blot were used to evaluate gene expression. In the co-cultures, type II collagen and aggrecan expression increased on days 14 and 21. At the mRNA level, the expression of type II collagen and aggrecan on day 21 was much higher in the 4:1, 2:1, and 1:1 groups than in either the articular chondrocyte group or the induced BMSC group, and the best ratio of co-culture groups seems to be 2:1. Also on day 21, the expression of type II collagen and aggrecan proteins in the 2:1 group was much higher than in all other groups. The results demonstrate that the co-culture of rabbit chondrocytes and rabbit BMSCs at defined ratios can promote the expression of cartilaginous extracellular matrix. The optimal cell ratio appears to be 2:1 (chondrocytes:BMSCs). This approach has potential applications in cartilage tissue engineering since it provides a protocol for maintaining and promoting seed-cell differentiation and function.