The model of accelerated senescence with the prolonged administration of d-galactose is used in anti-aging studies because it mimics several aging-associated alterations such as increase of oxidative stress and decline of cognition. However, there is no standardized protocol for this aging model, and recently some reports have questioned its effectiveness. To clarify this issue, we used a model of high-dose d-galactose on 1-month-old male Wistar rats and studied the hippocampus, one of the most affected brain regions. In one group (n = 10), d-galactose was daily administered intraperitoneally (300 mg/kg) during 8 weeks whereas age-matched controls (n = 10) were injected intraperitoneally with saline. A third group (n = 10) was treated with the same dose of d-galactose and with oral epigallocatechin-3-gallate (EGCG) (2 grams/L), a green tea catechin with anti-oxidant and neuroprotective properties. After treatments, animals were submitted to open-field, elevated plus-maze and Morris water maze tests, and neurogenesis in the dentate gyrus subgranular layer was quantified. There were no significant alterations when the three groups were compared in the number of doublecortin-and Ki-67-immunoreactive cells, and also on anxiety levels, spatial learning, and memory. Therefore, d-galactose was not effective in the induction of accelerated aging, and EGCG administered to d-galactose-treated animals did not improve behavior and had no effects on neurogenesis. We conclude that daily 300 mg/kg of d-galactose administered intraperitoneally may not be a suitable model for inducing age-related neurobehavioral alterations in young male Wistar rats. More studies are necessary to obtain a reliable and reproducible model of accelerated senescence in rodents using d-galactose.

Caloric restriction is able to delay age-related neurodegenerative diseases and cognitive impairment. In this study, we analyzed the effects of old-onset caloric restriction that started at 18 months of age, in the number of neuropeptide Y (NPY)-and somatostatin (SS)-containing neurons of the hippocampal formation. Knowing that these neuropeptidergic systems seem to be dependent of the cholinergic system, we also analyzed the number of cholinergic varicosities. Animals with 6 months of age (adult controls) and with 18 months of age were used. The animals aged 18 months were randomly assigned to controls or to caloric-restricted groups. Adult and old control rats were maintained in the ad libitum regimen during 6 months. Caloric-restricted rats were fed, during 6 months, with 60 % of the amount of food consumed by controls. We found that aging induced a reduction of the total number of NPY-and SS-positive neurons in the hippocampal formation accompanied by a decrease of the cholinergic varicosities. Conversely, the 24-month-oldonset caloric-restricted animals maintained the number of those peptidergic neurons and the density of the cholinergic varicosities similar to the 12-month control rats. These results suggest that the aging-associated reduction of these neuropeptide-expressing neurons is not due to neuronal loss and may be dependent of the cholinergic system. More importantly, caloric restriction has beneficial effects in the NPY-and SS-expressing neurons and in the cholinergic system, even when applied in old age.

Discussão: O ensino em meio clínico evidencia menor satisfação estudantil, traduzindo os elevados rácios em disciplinas clínicas. Dependendo do número de admissões, existem diferenças significativas entre Escolas. A qualidade das estratégias de ensino-aprendizagem e articulação hospitalar podem igualmente ser variáveis importantes. Conclusão:As Escolas com maior número de admissões podem ser mais suscetíveis a baixos resultados de satisfação estudantil. Elevados rácios estudante-tutor em disciplinas clínicas podem reduzir a qualidade do ensino em meio clínico e inibir a aquisição de competências.Palavras-chave: Alunos de Medicina; Educação Médica; Escolas Médicas; Portugal; Programas de Autoavaliação. ABSTRACT Introduction:Experiences of clinical and nonclinical learning environments, as well as assessment and study environments influence student satisfaction with their medical schools. Student-tutor ratios may impact on their perception of clinical learning environments. The aim of this study was to analyze medical students' satisfaction and student-tutor ratios in relation to medical schools' number of admissions. Material and Methods:A questionnaire was created, regarding learning, assessment and study environments in eight medical schools. 2037 students participated in this cross-sectional study. Cronbach's alpha (internal consistency) was calculated and principal component analysis was conducted. Pearson correlations and multiple comparisons were analyzed.Results: Assessment environments showed the highest satisfaction scores and clinical learning environments the lowest scores. The national student-tutor ratio in clinical rotations is 7.53; there are significant differences among schools. Institutions with higher number of admissions showed the lowest scores of overall student satisfaction (r = -0.756; p < 0.05), which decreased with progression in the medical course. High student-tutor ratios are strongly correlated with low levels of satisfaction regarding clinical learning environments (r = -0.826; p < 0.05).Discussion: Clinical learning environments show the lowest satisfaction scores, which may expose the effect of high ratios in clinical rotations. Depending on the number of admissions, significant differences between medical schools were found. Quality of teachinglearning strategies and articulation with hospitals might also be important variables. Conclusion:Medical schools with more admissions might be more susceptible to lower scores of student satisfaction. High studenttutor ratios in clinical rotations may reduce the quality of learning experiences and inhibit the acquisition of competences.