Search

The purpose of this study was to evaluate the behavior of the cardiac autonomic nervous system in adolescents with family history of hypertension at different levels of physical activity. The sample was composed for 162 adolescents who were divided into 2 groups: (a) offspring of normotensive; and (b) offspring of hypertensive that were subdivided into low and high levels of physical activity. The subjects underwent the following evaluations: anthropometric, level of physical activity, sexual maturation, sleep quality index, blood pressure, and heart rate variability. Significant differences (P<0.05) was observed at RMSSD, PNN50, Total Variance, HF, and LF. The findings indicate the practice of physical activity has a protector function on the cardiovascular system, which was linked to the decrease in sympathetic modulation along with a greater vagal response in adolescents with normotensive or hypertensive parents. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate body composition and nutritional status in 576 adolescents living in rural (RUR) and urban (URB) areas. The subjects were submitted to body composition and nutritional status assessments using the AnthroPlus software. Z-stature and Z-BMI calculations were performed. A multivariate logistic regression was also conducted and the Hosmer-Lemeshow test was used to verify the predictive capacity of the applied model. Statistical significance was set at an alpha level of P<0.05. The RUR adolescents showed significantly lower values of weight and height for age, while the adolescents of the URB demonstrated normality in these indices. In addition, adolescents in the RUR showed a risk of up to 6.29 times for short stature and 2.85 times for low weight, while adolescents of the URB presented a risk of 4.13 times for obesity. The RUR adolescents are at a high nutritional risk, while the URB adolescents are at a high risk for obesity. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the effect of wheelchair basketball practice in spinal cord injured subjects on autonomic modulation and sleep quality in 28 male wheelchair users. Subjects consisted of 12 healthy controls, 8 sedentary wheelchair users, and 8 wheelchair basketball players. Heart rate variability measurements (HRV) were carried out at rest. The wheelchair basketball group showed increased heart rate variability when compared to the sedentary wheelchair group, and, surprisingly, no difference was found when comparing basketball wheelchair and healthy controls subjects. The basketball practice did not influence the subjects' sleep quality. Thus, the findings indicate that basketball practice in patients with spinal cord injury causes significant improvement in HRV. [ABSTRACT FROM AUTHOR]

The understanding of the complexity of the space charge formation and movement inside insulation materials demands a high resolution measurement technique. The Kelvin Probe Force Microscopy (KPFM) can fulfill this demand. The KPFM delivers the data of the locally varying surface potential. They can be differentiated twice together with a reliable statistical approach to overcome the noise problem in the experimental surface potential data. In this way, we get the locally varying space charges according to the Poisson equation. This statistical approach has been tested by comparing the calculated space charge distributions from simulated and measured noisy surface potential data. The formation and the movement of space charges with respect to time under unbiased and biased conditions were investigated. [ABSTRACT FROM PUBLISHER]

We have explored for the first time PVDF Immobilon-P membranes, attached to interdigitated capacitor microelectrodes, as 3-D matrixes for the immobilization of antibodies in an interdigitated capacitive immunosensor format. The thick membranes allow distribution of antibodies across the entire region probed by the measuring electric field applied to the microelectrodes. This new approach is an alternative to the use of nanometer electrodes necessary to detect smaller layers of antibodies. As a proof-of-concept, a horseradish peroxidase (HRP) antibody/antigen affinity pair allowed for specific detection of the antigen in blocked membranes containing the antibody. Immobilization of antibody and penetration of antigen inside the PVDF membrane was assessed by fluorescence measurements and by an HRP enzymatic assay, respectively. The new interdigitated capacitive immunosensor was able to discriminate between buffer alone and HRP antigen in buffer, as proven by capacitance measurements. [ABSTRACT FROM PUBLISHER]

The relaxation properties of polymethacrylates of the n-alkyl series with n = l, 2 and 4 (poly(methyl methacrylate) ( PMMA), poly(ethyl methacrylate) ( PEMA) and poly( n-butyl methacrylate) ( PnBMA)) have been measured and analyzed in order to relate their properties to the size of the lateral side chains. The n-alkyl series has been regarded as a model system and was used in this work to test a graphical data analysis method. Essentially, four relaxation processes were detected in the three polymers: the γ, β, α and αβ relaxations, in increasing order of temperature. It was found that the γ relaxation has a low activation energy, of around 36.3-38.5 kJ mol−1, independent of the side chain, exhibiting low entropy of activation values when referring to the Eyring description of the activation parameters. The β relaxation was found to be similar in PMMA and PEMA, showing an activation energy of 88.8 kJ mol−1, increasing to 112.8 kJ mol−1 in PnBMA. The activation entropy was also found to be low for this relaxation, although greater than that for the γ relaxation. In contrast, the α relaxation is quite different in these polymers. We observed a gradual shift in the glass transition temperature towards lower temperatures as the side chain increases in length. The manner in which the α transition makes its way into the dielectric spectra is more abrupt in PMMA than in PnBMA, denoting a higher fragility in the former polymer. Finally, there is a significant difference in the coalescence scenarios of the α and β relaxations for temperatures higher than the glass transition temperature, where they give rise to the so-called αβ relaxation. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Barium zinc borosilicate glasses with a molar composition x BaO-(60− x) ZnO-30 B2 O3-10 SiO2, where x ranged from 0 to 60 mol%, were prepared using melt-quenching method. The effect of BaO substitution for ZnO on the sintering, crystallization, and dielectric characteristics has been investigated. The behavior of the studied barium zinc borosilicate glasses was mainly determined by the relative amount of the structural modifier oxides ( BaO and ZnO) and the ionic size, and field strength of the modifying cations ( Ba2+, Zn2+). Increased amounts of BaO decreased both glass transition temperature and crystallization temperature, while increasing the relative dielectric constant. Sintering occurred before crystallization for glasses where substitution of BaO for ZnO was up to 30 mol%, but for higher substitution levels, crystallization occurred during the sintering process hindering densification. [ABSTRACT FROM AUTHOR]

The article discusses the experimental process that looks at the evidence of electron injection from a silver cathode into a polyethylene terephthalate film, and electron extraction at the anode. It states that there is no charge transfer across the metal-semiconductor interface or metal-dielectric interface, when initially formed, since the barrier height for electron transfer depends on the work function of the metal in vacuum and modifications in the electrons of the applied field. The experiment indicates that there is no evidence of a threshold electric field for either injection or extraction at metal interfaces.

Aim: To compare the acute effects of two resistance exercise sessions with different partial blood flow restrictions (BFR) on hemodynamic parameters and cardiac autonomic modulation in older women with metabolic syndrome., Methods: Thirty-nine older women (64.4 ± 4.5 years) were allocated into three groups: BFR0 = resistance exercise (20%, 1 maximum repetition [MR]) + 0% BFR; BFR60 = 20% 1 MR resistance exercise + 60% BFR; and BFR80 = 20% 1MR resistance exercise + 80% BFR., Results: A reduction of 14 mmHg (BFR60 group) and 13 mmHg (BRF80 group) was observed 48 hr after the first exercise session, while vagal modulation was increased in the BRF60 group after 24 and 48 hr., Conclusion: A low-intensity resistance exercise session with 60% and 80% of BFR resulted in blood pressure (systolic, diastolic, and mean) reduction and positive changes on heart rate variability after 24 h of a RE session.

Background: Pulmonary Arterial Hypertension (PAH) is a severe and progressive disease of pulmonary arterioles. This pathology is characterized by elevation of the pulmonary vascular resistance and pulmonary arterial pressure, leading to right heart failure and death. Studies have demonstrated that resveratrol possesses a protective effect on the mechanisms related to the genesis of the PAH-induced by different models., Objective: This study aimed to investigate the dose-related effects of resveratrol in different models of pulmonary arterial hypertension., Methods: To identify eligible papers, we performed a systematic literature search on Scielo, Pub- Med, and Scholar Google. The research was limited to articles written in English in the last 10 years. We used the following descriptors to search: Pulmonary Arterial Hypertension and Resveratrol, OR Resveratrol, and Animal models of Pulmonary Arterial Hypertension, OR Resveratrol, and in vitro models of Pulmonary Arterial Hypertension., Results: 1724 studies were identified through the descriptors used, fifty-five studies with different models of pulmonary arterial hypertension were selected for the full review, forty-four were excluded after application of exclusion and inclusion criteria, totalizing eleven studies included in this systematic review., Conclusion: The results showed that resveratrol, at low and high doses, protects in a dosedependent manner against the development of PAH induced through monocrotaline, normoxia and hypoxia models. In addition to having chemopreventive, anti-inflammatory, antioxidant and antiproliferative properties. In the case of PAH-related myocardial injury, resveratrol protects cells from apoptosis, thus working as an antiapoptotic agent., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Breast cancer is one of the leading causes of death worldwide. Heart rate variability (HRV) has attracted scientific community attention in different pathologies, becoming thus an ultimate importance tool in both clinical and research setting, being a good predictor of cardiac events and mortality risk and also used in physical exercise and sports in general. The aim of the present study was to evaluate 12 weeks of exercise training and six weeks of detraining in cardiorespiratory capacity, and autonomic modulation in breast cancer patients., Methods: The sample was composed of 18 females (9 controls and 9 exercised), (aged 30-60 years). The HRV in the time and frequency domain was performed using an electrocardiogram before, after 12 weeks of the session of exercise training and after six weeks of detraining. Shapiro-Wilk and Mann-Whitney tests were made., Results: No significant changes in time domain were found. In the frequency domain, 12 weeks of exercise training promote a decrease in LF (nu) and decrease in HF (nu) Index. The exercise training period promoted a decrease in LF/HF. The autonomic data returned to baseline levels after the detraining period. However, cardiorespiratory capacity remained increased after the detraining period., Conclusions: These data demonstrated that exercise training can be used to prevent autonomic dysfunction in breast cancer patients, but detraining promotes loss of all autonomic benefits.