Dipeptidyl peptidase 4 (DPP4) regulates various physiological pathways and has a pivotal role in glucose homeostasis. The objective of this study was to verify the association of a haplotype constituted by two single nucleotide polymorphisms (rs2268894 and rs6741949) in the DPP4 gene with type 2 diabetes mellitus (T2DM) and fasting glycemia-related variables in a sample of Brazilian older adults, taking serum levels and enzymatic activity of DPP4 into account. Clinical, biochemical, and anthropometric characteristics as well as DPP4 serum levels and enzymatic activity were determined in 800 elderly (≥60 years old) individuals. Assessment of polymorphic sites was performed by real-time PCR whereas haplotypes were inferred from genotypic frequencies. Statistical analyses compared measures and proportions according to T2DM diagnosis and DPP4 haplotypic groups. The most common haplotype consisted of the T-rs2268894/G-rs6741949 string, which was 20% more frequent among non-diabetics. Considering non-diabetic patients alone, carriers of the T/G haplotype had significantly lower levels of blood glucose, insulin, HOMA-IR index, and DPP4 activity. Among diabetic patients, the T/G haplotype was associated with lower DPP4 levels whereas glycemic scores were not affected by allelic variants. Our results suggested that the genetic architecture of DPP4 affects the glycemic profile and DPP4 serum levels and activity among elderly individuals according to the presence or absence of T2DM, with a possible implication of the T/G haplotype to the risk of T2DM onset.

The present text will deal with aspects that should be carefully taken into account by researchers with the purpose of establishing sample size in studies in the areas of health, physical capacities and human development. It is important to highlight that sample calculation is not an exact science, and, as such, it requires realistic suppositions before estimation. It is observed that, despite great biotechnological advances that have contributed to faster scientific production, it is of vital importance that researchers commit to respect premises that enable the quality of the scientific work. In this regard, appropriate specifications of sample size grant internal validity to the study and must be a mandatory requisite for research projects approval.

O presente texto dissertará sobre aspectos que devem ser cuidadosamente ponderados por pesquisadores com o propósito de se estabelecer, a priori, o tamanho amostral em estudos na área da saúde, aptidão física e desempenho humano. Entretanto, é importante salientar que o cálculo de amostras é uma ciência que exige seguras suposições realistas, anterior à sua estimativa. Por fim, observamos que, apesar dos grandes avanços tecnológicos que têm contribuído para a maior velocidade de produção científica, é de vital importância que o pesquisador tenha o compromisso em respeitar premissas que habilitam a qualidade do trabalho científico. Nesse sentido, a apropriada especificação do tamanho amostral confere validade interna ao estudo e deve ser requisito obrigatório para a aprovação de projetos de pesquisa.

El presente texto versará sobre aspectos que deberían ser cuidadosamente ponderados por parte de los investigadores con el objetivo de establecer, a priori, el tamaño muestral de estudios en áreas de la salud, actividad física y rendimiento humano. Hay que resaltar que el cálculo del tamaño de la muestra no es una ciencia exacta y, por tanto, requiere suposiciones realistas previas a su estimación. Por último, observamos que, a pesar de los enormes avances biotecnológicos que han contribuido a una más rápida producción científica, es de vital importancia que los investigadores se comprometan a respetar premisas que permitan la calidad del trabajo científico. En este sentido, una adecuada especificación del tamaño muestral confiere validez interna al estudio y deben ser un requisito obligatorio para la aprobación de proyectos de investigación.

In maritime Antarctica soil enzymes have been little researched, mainly in the rhizosphere of the only two vascular plants that grow there: Colobanthus quitensis and Deschampsia antarctica. This study evaluated the activities of hydrolytic enzymes β-glucosidase, phosphatase and urease in the rhizospheric soils of C. quitensis and D. antarctica from three different sites in the Polish Arctowski Station in Antarctica. The sensitivity to temperature changes of the enzymes was also evaluated using two incubation temperatures (37 and 12 °C). The highest activities related to the C and P cycles, β-glucosidase and acid phosphatase, respectively, were detected in the rhizospheric soils at the site with the greatest variety of plant cover. Urease activity, related to the N cycle, was high in two of the three sites, and the lowest activity was detected at the site where only D. antarctica was found. The activity of the enzymes decreased when the temperature of incubation was reduced, but the magnitude of the decrease depended on the enzyme. β-glucosidase was the most sensitive to temperature change, whereas urease was least affected. Therefore, temperature changes in rhizospheric soils could lead to changes in substrate degradation rates and consequently in the availability of nutrients (C, N and P) for C. quitensis and D. antartica in maritime Antarctica.

The potential soil biological change due to the establishment of Eucalyptus plantations in volcanic soils has not been reported. The objective of this research was to assess the soil quality of Eucalyptus stands growing on a volcanic ash derived soil, compared with a natural forest (Nat-forest, control) and a Pinus radiata stand, previously established to the Eucalyptus stand. A complete randomised design was established (n=4) within Nat-forest and commercial plantations. Soil samples (10 cm) were taken in autumn, to measure soil microbial biomass (Cbiom) by soil fumigation-extraction, and CO2-C respiration (Cmin) from soil microorganisms by soil incubation. Metabolic quotient (q met) was calculated to compare (p ≤ 0.05) the microbial efficiency of the soil biomass between treatments. As expected, Nat- forest showed the largest Cbiom and Cmin (p ≤ 0.05). However, no differences were found between E. globulus, E. nitens and P. radiata (p ≤ 0.05). The low Cbiom and Cmic in Eucalyptus stands might be attributed to the effect of recalcitrant inputs of C from the previous pine plantation, although the efficiency of the soil microbial population (q met) was not affected (p ≤ 0.05) by the C quality of the plantations. Thus, it seems that Eucalyptus stands are not entirely detrimental to the soil quality of volcanic soils of temperate forest ecosystems.

The objective of the present study was to compare the effect of acute exercise performed at different intensities in relation to the anaerobic threshold (AT) on abilities requiring control of executive functions or alertness in physically active elderly females. Forty-eight physically active elderly females (63.8 ± 4.6 years old) were assigned to one of four groups by drawing lots: control group without exercise or trial groups with exercise performed at 60, 90, or 110% of AT (watts) and submitted to 5 cognitive tests before and after exercise. Following cognitive pretesting, an incremental cycle ergometer test was conducted to determine AT using a fixed blood lactate concentration of 3.5 mmol/L as cutoff. Acute exercise executed at 90% of AT resulted in significant (P < 0.05, ANOVA) improvement in the performance of executive functions when compared to control in 3 of 5 tests (verbal fluency, Tower of Hanoi test (number of movements), and Trail Making test B). Exercising at 60% of AT did not improve results of any tests for executive functions, whereas exercise executed at 110% of AT only improved the performance in one of these tests (verbal fluency) compared to control. Women from all trial groups exhibited a remarkable reduction in the Simple Response Time (alertness) test (P = 0.001). Thus, physical exercise performed close to AT is more effective to improve cognitive processing of older women even if conducted acutely, and using a customized exercise prescription based on the anaerobic threshold should optimize the beneficial effects.

In worldwide studies, interleukin-6 (IL-6) is implicated in age-related disturbances. The aim of the present report was to determine the possible association of IL-6 -174 C/G promoter polymorphism with the cytokine profile as well as with the presence of selected cardiovascular risk features. This was a cross-sectional study on Brazilian women aged 60 years or older. A sample of 193 subjects was investigated for impaired glucose regulation, diabetes, hypertension, and dyslipidemia. Genotyping was done by direct sequencing of PCR products. IL-6 and C-reactive protein were quantified by high-sensitivity assays. General linear regression models or the Student t-test were used to compare continuous variables among genotypes, followed by adjustments for confounding variables. The chi-square test was used to compare categorical variables. The genotypes were consistent with Hardy-Weinberg equilibrium proportions. In a recessive model, mean waist-to-hip ratio, serum glycated hemoglobin and serum glucose were markedly lower in C homozygotes (P = 0.001, 0.028, and 0.047, respectively). In a dominant hypothesis, G homozygotes displayed a trend towards higher levels of circulating IL-6 (P = 0.092). Non-parametric analysis revealed that impaired fasting glucose and hypertension were findings approximately 2-fold more frequent among G homozygous subjects (P = 0.042 and 0.043, respectively). Taken together, our results show that the IL-6 -174 G-allele is implicated in a greater cardiovascular risk. To our knowledge, this is the first investigation of IL-6 promoter variants and age-related disturbances in the Brazilian elderly population.