Hormonal, autonomic cardiac and mood states changes during an Antarctic expedition: From ship travel to camping in Snow Island.

We evaluated the influence of an Antarctic expedition, consisting of 26-day ship travel followed by 24-day camping in the Antarctic field during the summer season, on hormonal responses, autonomic cardiac control, and mood states in individuals that live in tropical regions. Data collection was carried out in 10 individuals on the 2nd, 16th, and 26th days aboard the ship (characterized by exposure to low-luminosity and temperature-controlled environments) and on the 4th, 11th, and 23rd days of camping in the Antarctic field (prolonged exposure to natural luminosity and cold environments). Morning samples of saliva (to determine testosterone and cortisol concentrations) and blood [to determine thyroid-stimulating hormone (TSH) and thyroxine (T4) concentrations] were obtained. Next, resting heart rate variability (HRV) was recorded, and the volunteers answered a mood questionnaire. Samples of saliva for measurement of melatonin concentration were obtained at night. At the end of ship travel, blood TSH and salivary melatonin increased by 15.6% and 72.3%, respectively, whereas salivary cortisol reduced by 37.1% compared to initial values and T4 reduced by 12.2% compared to 16th day. These hormonal changes occurred alongside increased depression score and biphasic changes in HRV parameters; for example, the RMSSD, a parasympathetic-related parameter, initially decreased by 47.8% and then returned towards baseline values by the end of the ship travel. In contrast, during the camp period, blood TSH and T4 reduced by 26.5% and 34.1%, respectively, and salivary cortisol increased by 72.1%, without concomitant changes in melatonin and HRV. Also, tension score transiently reduced and then increased towards the pre-camp score by the end of the field period. Testosterone remained unaltered throughout the expedition. In conclusion, ship travel and camping in Antarctica induced distinct neuroendocrine changes, cardiac autonomic regulation, and mood states. These specific changes most likely resulted from exposure to different natural luminosity, degrees of confinement, and ambient temperature in these environments.

Association between C reactive protein and all-cause mortality in the ELSA-Brasil cohort.

BACKGROUND: High-sensitivity C reactive protein (hsCRP) has been proposed as a marker of incident cardiovascular disease and vascular mortality, and may also be a marker of non-vascular mortality. However, most evidence comes from either North American or European cohorts. The present proposal aims to investigate the association of hsCRP with the risk of all-cause mortality in a multiethnic Brazilian population. METHODS: Baseline data (2008-2010) of a cohort of 14 238 subjects participating in the Brazilian Longitudinal Study of Adult Health were used. hsCRP was assayed with immunochemistry. The association of baseline covariates with all-cause mortality was calculated by Cox regression for univariate model and adjusted for different confounders after a mean follow-up of 8.0±1.1 years. The final model was adjusted for age, sex, self-rated race/ethnicity, schooling, health behaviours and prevalent chronic disease. RESULTS: The risk of death increased steadily by quartiles of hsCRP, from 1.45 (95% CI 1.05 to 2.01) in quartile 2 to 1.95 (95% CI 1.42 to 2.69) in quartile 4, compared with quartile 1. Furthermore, the persistence of a significant graded association after the exclusion of deaths in the first year of follow-up suggests that these results are unlikely to be due to reverse causality. Finally, the HR was unaffected by the exclusion of participants who had self-reported medical history of diabetes, cancer and chronic obstructive pulmonary disease. CONCLUSIONS: Our study shows that hsCRP level is associated with mortality in a highly admixed population, independent of a large set of lifestyle and clinical variables.

The changes in maximal oxygen uptake (V̊O2MAX) induced by physical exertion during an Antarctic expedition depend on the initial V̊O2MAX of the individuals: a case study of the Brazilian expedition.

Antarctic climate is challenging, since the cold, wind and sensory monotony are stressful stimuli to individuals. Moreover, camp activities and heavy clothes may contribute to increase physiological strain. Thus, we aimed to characterise the physiological demand of a 24-day period in the Antarctic field and then to evaluate the effect of this expedition on the aerobic fitness in individuals with heterogeneous initial aerobic fitness (as determined by estimating maximum oxygen consumption - V̊O2MAX). Before and after the 24-day period in Antarctica, 7 researchers and 2 mountaineers were subjected to incremental tests to estimate their V̊O2MAX. Field effort was characterised by measuring heart rate (HR). During the field trips, their HR remained 33.4% of the recording time between 50-60% HRMAX, 22.3% between 60-70% HRMAX, and only 1.4% between 80 and 90% HRMAX. The changes in estimated V̊O2MAX during the expedition depended on the pre-expedition aerobic fitness. The post-expedition V̊O2MAX increased by 5.9% and decreased by 14.3%in individuals with lower (researchers) and higher (mountaineers) initial V̊O2MAX, respectively. We concluded that physical effort in the Antarctic field is characterised as predominantly of low- to moderate-intensity. This effort represented an effective training load for individuals with lower initial V̊O2MAX, but not for those with higher V̊O2MAX.

Non-HDL-C goals based on the distribution of population percentiles in ELSA-Brasil: Is it time to change?

BACKGROUND AND AIMS: Non-high-density lipoprotein cholesterol (non-HDL-C) goals are defined as 30 mg/dL (0.78 mmol/L) higher than the respective low-density lipoprotein cholesterol (LDL-C) goals. This definition, however, do not consider the population distribution of non-HDL-C, which could represent a more appropriate individual goal when both markers are discordant. The aim of this study is to establish non-HDL-C goals at the same population percentiles of LDL-C. METHODS: Non-HDL-C values were assigned at the same percentiles correspondent to the LDL-C treatment goals for 14,837 participants from the Longitudinal Study of Adult Health (ELSA-Brasil) with triglycerides levels ≤ 400 mg/dL (4.52 mmol/L). We also assessed the frequency of reclassification, defined as the number of subjects with LDL-C levels in the recommended therapeutic category, but with non-HDL-C levels above or below the category. RESULTS: The non-HDL-C values, based on correspondent LDL-C population percentiles, were 92 (2.38), 122 (3.16), 156 (4.04), 191 (4.95), and 223 mg/dL (5.78 mmol/L). Among participants with LDL-C <70 mg/dL (1.81 mmol/L), 22.8% were reclassified in a higher category according to the guidelines-based non-HDL-C cut-off and 30.1% according to the population percentile-based cut-off; 25.6% and 64.1%, respectively, if triglycerides concurrently 150-199 mg/dL (1.69-2.25 mmol/L). CONCLUSIONS: Our results demonstrated that non-HDL-C percentiles-based goals were up to 8 mg/dL (0.21 mmol/L) lower than the guidelines recommended goal and had a profound impact on the reclassification of participants, notably when LDL-C was <100 mg/dL (2.56 mmol/L), the treatment goal for high risk patients. Therefore, non-HDL-C goals should be changed for reduction of residual risk.

Platelet volume is associated with the Framingham risk score for cardiovascular disease in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

BACKGROUND: Platelet volume indices (PVI), an easy and inexpensive surrogate measure of platelet function, have been associated with cardiovascular diseases (CVD) and their risk factors. However, results are conflicting because of the lack of standardized procedures. The purpose of this study is to investigate the relationship of PVI with the Framingham risk score (FRS). METHODS: Baseline data (2008-2010) of 3115 participants enrolled in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) were used. PVI measurements were strictly controlled. The cohort was distributed according to risk factors and the general FRS was estimated. Multiple linear regression analysis was used to estimate the association between PVI and FRS. RESULTS: Mean platelet volume (MPV), platelet distribution width (PDW) and platelet large cell ratio (P-LCR) independently correlated (p≤0.01) with FRS after adjustment for confounding variables. One unit increase in MPV, PDW, or P-LCR increased the FRS by 0.59%, 0.40%, and 0.08%, respectively. Diabetics had higher (p≤0.004) MPV, PDW, and P-LCR, and hypertensive individuals had higher (p≤0.045) PDW and P-LCR. CONCLUSIONS: Increased PVI was independently correlated with higher CVD risk based on the FRS, diabetes, and systolic hypertension. Prospective follow up of this cohort is warranted to confirm that PVI is associated with the development of CVD.

Standardization and reference intervals of platelet volume indices: Insight from the Brazilian longitudinal study of adult health (ELSA-BRASIL).

Platelet volume indices (PVI) are associated with hematological and non-hematological diseases, notably cardiovascular and cerebrovascular diseases. The establishment of PVI reference intervals (RIs) are essential to evaluate whether these indices are useful in clinical practice. Healthy-associated RIs have not yet been established for the Brazilian population. Here, we determined RIs of PVI for a health adult population, participants of the Brazilian Longitudinal Study of Adult Health ELSA-Brasil. A total of 580 individuals out of an initial sample of 3115 subjects constituted the healthy reference sample. To be part of the study, individuals had to fulfill the following criteria: blood count within 2 hours of collection, no use of continuous medication, self-rated health as good or very good, no reported diagnosis of diabetes and/or arterial hypertension, not smoking, lack of metabolic syndrome, body mass index (BMI) <30 kg/m(2), and platelet, hemoglobin, and creatinine beyond reference values. The RIs are mean platelet volume (MPV): 8.9-11.8 fL, platelet distribution width (PDW): 9.6-15.3 fL, platelet large cell ratio (P-LCR): 15.6-39.5%. These parameters were not significantly affected by age, gender, smoking, obesity, and alcohol abuse. However, significant differences were found among self-rated race/color groups. Standardization of measurement procedures and the establishment of healthy-associated PVI RIs are essential to be able to support clinical decision-making from laboratorial test results. This study at the baseline of the ELSA Brasil reported herein may contribute to future efforts aiming to evaluate whether PVI values are associated with clinical conditions in the Brazilian population.