1,720,992 research outputs found
Heart-rate changes after an ultraendurance swim from Italy to Albania: A case report
No full textPurpose: To evaluate the effect of a solo ultraendurance open-water swim on autonomic and nonautonomic control of heart rate (HR). Methods: A male athlete (age 48 y, height 172 cm, body mass 68 kg, BMI 23 kg/m2) underwent HR-variability (HRV) and circulating catecholamine evaluations at different times before and after an ultraendurance swim crossing the Adriatic Sea from Italy to Albania. HRV was measured in 5-min segments and quantified by time and frequency domain. Circulating catecholamines were estimated by salivary alpha-amylase (sAA) assay. Results: The athlete completed 78.1 km in 23:44 h:min. After arrival, sAA levels had increased by 102.6%. Time- And frequency-domain HRV indexes decreased, as well (mean RR interval, -29,7%; standard deviation of normal mean RR interval, -63,1%; square root of mean squared successive differences between normal-to-normal RR intervals, -49.3%; total power, -74.3%; low frequency, -78.0%; high frequency, -76.4%), while HR increased by 41.8%. At 16-h recovery, sAA had returned to preevent values, while a stable tachycardia was accompanied by reduced HRV measures. Conclusion: To the authors' knowledge, this is the first study reporting cardiac autonomic adjustments to an extreme and challenging ultraendurance open-water swim. The findings confirmed that the autonomic drives depend on exercise efforts. Since HRV changes did not mirror the catecholamine response 16 h postevent, the authors assume that the ultraendurance swim differently influenced cardiac function by both adaptive autonomic and nonautonomic patterns
Activity of Autonomic Nervous System, Energy Expenditure and Assessment of Oxidative Stress in Menopause-women Using Hormone Replacement Therapy
No full textAims: Menopause is a period of significant physiological change that may be associated with
increased body weight and obesity-related diseases. Many studies have been carried out to
determine influences of estrogen depletion, resting energy expenditure (REE) decline and aging
during menopause-related obesity.
Methodology: In the present experiment, REE, body composition, activity of the autonomic
nervous system, oxidative stress and food intake were measured in three groups of women: premenopause
(n=40), post-menopause with hormone-replacement therapy (HRT) (n=40) and postmenopause
without HRT (n=40).
Results: In post-menopause women with HRT a significant increase was found in: 1) the
sympathetic activity, measured by the power spectral analysis of the heart rate variability; 2) REE,
measured by indirect calorimetry; 3) oxidative stress, measured by Free Radical Analytical System
4 (Fras-4) compared to the value of the other two, while fat mass, measured by Body Impedance
Analysis (BIA), was reduced in favor of a recovery of free fat mass.
Conclusion: The study emphasizes the important changes due to HRT on various components
influencing body weight in menopause-women
Effects of Emotional Stress on Neuroendocrine and Autonomic Functions in Skydiving
No full textBy using a psycho-physiological approach we investigated the stress response during parachute jumping, a well- characterized stress model to study emotional and physical stress in humans. Besides the observation of hormone reactivity in response to such a short-term stressful event, this study focused on the correlations among competitive state anxiety components, hormonal and autonomic responses. Seven male sport-parachutists, aged 35.7 ± 17.5 years, took part in the study after giving their informed consent. Neuroendocrine and autonomic variables were measured 12 h before jumping (basal), within 60 s (jump) and 90 min after touching the ground (post-jump). Prior to boarding, participants were administered the Competitive State Anxiety Inventory-2 (CSAI-2) questionnaire. Salivary cortisol (Cort) and α-amylase (A-A) concentrations were measured by spectrophotometry using commercial kits. For heart rate (HR) and galvanic skin response (GSR) assessments data were acquired by holter recording, within an interval time of 5 min following saliva collection. Parachute jumping led to a strong response of Cort, A-A, as well as HR and GSR, as shown by the values noted as basal and at jump, meaning that the psychological arousal linked to this condition acts on different systems. In examining bioumoral correlates and psychological measures of stress and anxiety we found correlations between neuroendocrine parameters and anxiety components. However, no relationship between Cort and somatic or cognitive anxiety was noted, suggesting that this physiological measure is not a good index of stress during parachuting. As revealed by the differences in cognitive or somatic state anxiety, stress related to sport parachuting differentially affected salivary indices. Alpha-amylase seems to be a better physiological indicator than cortisol to examine the relationship between neuroendocrine parameters and state anxiety components. Finally, this is the first report that GSR significantly correlated with A-A and the somatic component of competitive state anxiety, confirming its potential to provide researchers with a tool for objectively measuring stress during operational conditions. On the whole, these findings have contributed to our understanding of hormone-behavior relationships
Physical Activity as a New Tool to Evaluate the Response to Omalizumab and Mepolizumab in Severe Asthmatic Patients: A Pilot Study
No full textAsthma is a chronic inflammatory airway disease, representing one of the most severe pathologies in developed countries. Based on a report of the World Health Organization (WHO), it affects about 300 million people worldwide. Few studies have analyzed the effects of daily life physical activity (PA) levels in patients with asthma: moreover, little research has been carried out on PA levels in patients suffering from severe asthma (SA). This study aimed to investigate the PA levels in two groups of patients suffering from SA; in particular, this study analyzed the changes that occur in patients treated with biologic therapy (BT group) and patients who underwent traditional treatment (TT group) over 6 months. Moreover, this study represents a pilot study because, to the best of our knowledge, it is the first investigation that analyzed if the kind of biologic drug (omalizumab or mepolizumab) can produce differences in the PA levels of SA patients. Fifty SA patients were enrolled and PA parameters were monitored for 6 months. Subjects were divided into two treatment groups: TT (20 patients) and BT (30 patients), the BT group was further subdivided according to the drugs used (15, omalizumab; 15, mepolizumab). During drug treatment, all subjects improved their PA levels: indeed, considering the intragroup variation, the PA levels were significantly higher comparing the T6 levels to baseline (T0, p < 0.01). Considering the intragroup variation, it is very interesting to note that biologic therapy improved PA levels compared to the effects of traditional therapy; while at T0 there were no significant differences in the steps per day (SPD) values between the two groups (T0, p = 0.85), the differences become statistically significant at T1, T3, and T6 (T1, p = 0.019; T3, p = 3.48x10(-6); T6, p = 4.78x10(-10)). As expected, the same differences were reported analyzing the energy expenditure data. In conclusion, this pilot study reports a positive relationship between biologic drug therapy and PA patterns, even if further studies are needed
Heart rate variability is reduced in underweight and overweight healthy adult women
No full textHeart rate variability (HRV) is altered in obese subjects, but whether this is true also in underweight (UW) subjects is still under debate. We investigated the HRV profile in a sample of healthy adult women and its association with adiposity. Five-minute resting state electrocardiographic activity was recorded in 69 subjects grouped according to their body mass index, [23 normal weight (NW), 23 overweight/obese (OW) and 23 UW). Body fat mass (FM) was measured by bio-impedance. Frequency- and time-domain analyses were performed. Compared to NW, UW and OW subjects showed a significant decrease in HRV indices, as revealed by spectral analysis. No differences were observed between UW and OW subjects. A second-order polynomial regression unveiled an inverted U-shaped relationship between FM extent and HRV indices. A decrease of HRV indices was associated with changes in FM extent, proving that in UW and OW subjects, the adaptive flexibility of autonomic cardiac function was reduced. These findings provide important clues to guide future studies addressed to determine how changes in adiposity and autonomic cardiac function may contribute to health risk
Heart rate variability reduction is related to a high amount of visceral adiposity in healthy young women
No full textSeveral heart rate variability (HRV) studies show abnormalities in autonomic nervous control in obese and overweight subjects. However, some of the results appear to be controversial. Here we investigate the HRV profile in seventy adult normotensive women and its association with general and visceral adiposity. Specifically, we recorded the electrocardiographic (ECG) activity in subjects during a supine resting state for five minutes in a quiet room late in the morning. Total fat mass (TFM) and visceral adipose tissue (VAT) were instead estimated using dual-energy X-ray absorptiometry (DXA). Finally, we used simple a linear regression analysis of frequency and time-domain parameters to study the relationship between HRV and adiposity. Our data showed an overall reduction of the HRV related to an increase of TFM although this regression appeared significant only for high frequencies (HF). When the linear regression was applied between HRV variables and VAT, the slope of the line increases, thus unveiling a statistically significant relation (i.e. the more VAT, the lower HRV). Finally, a control analysis showed that age does not alter the relation between HRV and VAT when used as a confounding factor in multiple regression. To conclude, these findings point to abnormal activity of the autonomic nervous system (ANS) in subjects with an excess of VAT and represent a starting point to determine a non-invasive index of cardiac wellness for clinical and nutritional application.</div
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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