1,721,307 research outputs found
Psychophysiological risk markers of cardiovascular disease
No full texthttp://dx.doi.org/10.1016/j.neubiorev.2009.11.00
Sympathetic nervous activity, depressive symptoms, and metabolic syndrome in black Africans: the sympathetic activity and ambulatory blood pressure in Africans study
No full textThe aim of this study was to examine the association between sympathetic nervous activity, depressive symptoms, and metabolic syndrome in a sample of black and Caucasian Africans. The sample consisted of healthy men and women: 194 blacks (aged, mean ± SD, 44.1 ± 7.9 years) and 206 Caucasians (aged, mean ± SD, 44.7 ± 10.8 years). Salivary 3-methoxy-phenylglycol (MHPG) concentration, the major metabolite of norepinephrine, was measured during the Stroop mental challenge. Depressive symptoms were assessed from the 9-item Patient Health Questionnaire. Metabolic syndrome (defined as central obesity plus any other two risk factors including raised serum triglycerides, reduced serum high-density lipoprotein- cholesterol, raised blood pressure, and raised fasting plasma glucose) was prevalent in 43.0% and 36.4% of blacks and Caucasians, respectively. In blacks there was, on average, a 16.4% increase in salivary MHPG concentration following mental stress, although no significant response was observed in Caucasians. The salivary MHPG response in blacks was associated with risk of metabolic syndrome (odds ratio [OR] = 1.11, 95% CI, 1.00–1.24) after adjusting for age, sex, and baseline salivary MHPG concentration. This association was mainly driven by the central obesity component of the metabolic syndrome. The salivary MHPG response was also related to moderate-severe depressive symptoms (OR = 1.16, 95% CI, 1.04–1.30), and further adjustment for depressive symptoms attenuated the association between salivary MHPG response and metabolic syndrome (OR = 1.07, 95% CI, 0.96–1.20). These data indicate an association between sympathetic activity, depressive symptoms, and metabolic syndrome in a sample of black African
Comparison of telomere length in black and white teachers from South Africa: the sympathetic activity and ambulatory blood pressure in Africans study
Get PDFOBJECTIVE
Telomere length is a marker of biological aging that has been linked to cardiovascular disease risk. The black South African population is witnessing a tremendous increase in the prevalence of cardiovascular disease, part of which might be explained through urbanization. We compared telomere length between black South Africans and white South Africans and examined which biological and psychosocial variables played a role in ethnic difference in telomere length.
METHODS
We measured leukocyte telomere length in 161 black South African teachers and 180 white South African teachers aged 23 to 66 years without a history of atherothrombotic vascular disease. Age, sex, years having lived in the area, human immunodeficiency virus (HIV) infection, hypertension, body mass index, dyslipidemia, hemoglobin A1c, C-reactive protein, smoking, physical activity, alcohol abuse, depressive symptoms, psychological distress, and work stress were considered as covariates.
RESULTS
Black participants had shorter (median, interquartile range) relative telomere length (0.79, 0.70-0.95) than did white participants (1.06, 0.87-1.21; p < .001), and this difference changed very little after adjusting for covariates. In fully adjusted models, age (p < .001), male sex (p = .011), and HIV positive status (p = .023) were associated with shorter telomere length. Ethnicity did not significantly interact with any covariates in determining telomere length, including psychosocial characteristics.
CONCLUSIONS
Black South Africans showed markedly shorter telomeres than did white South African counterparts. Age, male sex, and HIV status were associated with shorter telomere length. No interactions between ethnicity and biomedical or psychosocial factors were found. Ethnic difference in telomere length might primarily be explained by genetic factors
Three-year changes of prothrombotic factors in a cohort of South Africans with a high clinical suspicion of obstructive sleep apnea.
No full textA hypercoagulable state might be one important mechanism linking obstructive sleep apnea (OSA) with incident myocardial infarction and stroke. However, previous studies on prothrombotic factors in OSA are not uniform and cross-sectional. We longitudinally studied prothrombotic factors in relation to OSA risk, adjusting for baseline levels of prothrombotic factors, demographics, metabolic parameters, aspirin use, and life style factors. The Berlin Questionnaire and/or neck circumference were used to define high OSA risk in 329 South African teachers (48.0 % male, 44.6 % black) at baseline and at three-year follow-up. Von Willebrand factor (VWF), fibrinogen, D-dimer, plasminogen activator inhibitor-1, clot lysis time (CLT), and soluble urokinase-type plasminogen activator receptor (suPAR) were measured in plasma. At baseline 35.7 % of participants had a high risk of OSA. At follow-up, persistently high OSA risk, persistently low OSA risk, OSA risk remission, and new-onset OSA risk were present in 26.1 %, 53.2 %, 9.4 %, and 11.3 % of participants, respectively. New-onset OSA risk was associated with a significant and longitudinal increase in VWF, fibrinogen, CLT, and suPAR relative to persistently low OSA risk; in VWF, fibrinogen, and suPAR relative to remitted OSA risk; and in VWF relative to persistently high OSA risk. Persistently high OSA risk was associated with an increase in CLT and suPAR relative to persistently low OSA risk and in D-dimer relative to remitted OSA risk. Remitted OSA risk was associated with D-dimer decrease relative to persistently low OSA risk. In OSA, hypercoagulability is a dynamic process with a most prominent three-year increase in individuals with new-onset OSA risk
Overweight, obesity, and risk of hospitalization for COVID-19: A community-based cohort study of adults in the United Kingdom
No full textThe role of obesity and overweight in occurrence of COVID-19 is unknown. We conducted a large-scale general population study using data from a community-dwelling sample in England (n = 334,329; 56.4 ±8.1 y; 54.5% women) with prospective linkage to national registry on hospitalization for COVID-19. Body mass index (BMI, from measured height and weight) was used as an indicator of overall obesity, and waist−hip ratio for central obesity. Main outcome was cases of COVID-19 serious enough to warrant a hospital admission from 16 March 2020 to 26 April 2020. Around 0.2% (n = 640) of the sample were hospitalized for COVID-19. There was an upward linear trend in the likelihood of COVID-19 hospitalization with increasing BMI, that was evident in the overweight (odds ratio, 1.39; 95% CI 1.13 to 1.71; crude incidence 19.1 per 10,000) and obese stage I (1.70;1.34 to 2.16; 23.3 per 10,000) and stage II (3.38; 2.60 to 4.40; 42.7 per 10,000) compared to normal weight (12.5 per 10,000). This gradient was little affected after adjustment for a wide range of covariates; however, controlling for biomarkers, particularly high-density lipoprotein cholesterol and glycated hemoglobin, led to a greater degree of attenuation. A similar pattern of association emerged for waist−hip ratio. In summary, overall and central obesity are risk factors for COVID-19 hospital admission. Elevated risk was apparent even at modest weight gain. The mechanisms may involve impaired glucose and lipid metabolism
Low serum testosterone and increased diastolic ocular perfusion pressure: a risk for retinal microvasculature
No full textBACKGROUND
Low levels of testosterone in men and changes in retinal microvascular calibre are both associated with hypertension and cardiovascular disease risk. Sex hormones are also associated with blood flow in microvascular beds which might be a key intermediate mechanism in the development of hypertension. Whether a direct association between endogenous testosterone and retinal microvascular calibre exists is currently unknown. We aimed to determine whether testosterone is independently associated with ocular perfusion via a possible association with retinal vascular calibre or whether it plays only a secondary role via its effect on blood pressure in a bi-ethnic male cohort.
PROBANDS AND METHODS
A total of 72 black and 81 white men (28-68 years of age) from the follow-up phase of the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study were included in this sub-study. Ambulatory pulse pressure and intraocular perfusion pressures were obtained, while metabolic variables and testosterone were measured from fasting venous blood samples. Retinal vascular calibre was quantified from digital photographs using standardised protocols.
RESULTS
The black men revealed a poorer cardiometabolic profile and higher pulsatile pressure (>50 mm Hg), intraocular pressure and diastolic ocular perfusion pressure than the white men (p≤0.05). Only in the white men was free testosterone positively associated with retinal calibre, i.e. arterio-venular ratio and central retinal arterial calibre and inversely with central retinal venular calibre. These associations were not found in the black men, independent of whether pulse pressure and ocular perfusion pressure were part of the model.
CONCLUSIONS
These results suggest an independent, protective effect of testosterone on the retinal vasculature where an apparent vasodilatory response in the retinal resistance microvessels was observed in white men
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Effects of acute and chronic stress on the L-arginine nitric oxide pathway in black and white South Africans: the sympathetic activity and ambulatory blood pressure in Africans study
No full textOBJECTIVE:
This study investigated the impact of stress on effectors of the L-arginine/nitric oxide (NO) system including the endogenous inhibitor asymmetric dimethylarginine (ADMA).
METHODS:
Black (n = 168) and white (n = 206) South African teachers were exposed to a mental and a physical stressor for 1 minute, respectively. Serum samples for determination of l-arginine, NO metabolites, ADMA, and symmetric dimethylarginine (SDMA) were obtained at rest and during stress exposure. Perception of task stressfulness was assessed on a 7-point Likert scale, and psychological distress was estimated by the General Health Questionnaire.
RESULTS:
Black South Africans exhibited higher resting levels of NO metabolites (adjusted mean [standard error of the mean] = 11.3 [1.3] versus 3.9 [1.1] μmol/l, p < .001) but lower circulating ADMA (0.62 [0.02] versus 0.70 [0.02] μmol/l, p = .004) and SDMA (0.41 [0.01] versus 0.53 [0.01] μmol/l, p < .001) than did white South Africans. Ethnicity-by-psychological distress interaction was observed for resting levels of ADMA (p = .002), SDMA (p = .038), and L-arginine (p = .048). Ethnic differences in responses to experimental stress were evident for NO metabolites (blacks versus whites: 5.94 [1.55] versus -0.74 [1.25] μmol/l, p = .004) and SDMA (blacks versus whites: -0.02 [0.01] versus 0.02 [0.01] μmol/l, p = .004). Ethnicity-by-psychological distress interaction for stress responses was found for l-arginine/ADMA ratio (p = .027).
CONCLUSIONS:
The l-arginine/NO system is affected by psychosocial distress with higher susceptibility in black South Africans. This interaction may contribute to the higher cardiovascular disease risk in black South African
Variations on the Author
Get PDF“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
- …
