Browsing Research Output by Author "22684808 - Hamer, Mark"
Now showing items 1-20 of 25
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The association between seven-day objectively measured habitual physical activity and 24 h ambulatory blood pressure: the SABPA study
Hamer, M.; Bruwer, E.J.; De Ridder, J.H.; Swanepoel, M.; Cockeran, M.; Malan, L. (Springer Nature, 2017)Few studies have examined objective physical activity in relation to 24 h ambulatory blood pressure (BP). We aimed to assess the association of 7-day objectively measured habitual physical activity with ambulatory BP in a ... -
Blunted neuro-endocrine responses linking depressive symptoms and ECG left ventricular hypertrophy in black Africans: the SABPA study
Mashele, Nyiko; Malan, Leoné; Van Rooyen, Johannes M.; Harvey, Brian H.; Potgieter, Johan C.; Hamer, Mark (Wolters Kluwer, 2014)Objective: Chronic psychosocial stress as experienced in an urban environment plays an important role in the aetiology of depression-related cardiovascular risk. It is uncertain whether acute mental stress responses aggravate ... -
Chronic defensiveness and neuroendocrine dysfunction reflect a novel cardiac troponin T cut point: the SABPA study
Malan, Leoné; Hamer, Mark; Von Känel, Roland; Steyn, Hendrik S.; Malan, Nicolaas T. (Elsevier, 2017)Background Sympatho-adrenal responses are activated as an innate defense coping (DefS) mechanism during emotional stress. Whether these sympatho-adrenal responses drive cardiac troponin T (cTnT) increases are unknown. ... -
Chronic depression symptoms and salivary NOx are associated with retinal vascular dysregulation: the SABPA study
Malan, Leoné; Hamer, Mark; Von Känel, Roland; Harvey, Brian H.; Steyn, Faans; Malan, Nico T. (Elsevier, 2016)Background Depression has been associated with impaired nitric oxide (NO)-mediated vasodilation and vascular dysregulation (VD). Whether depression and NO levels will disturb retinal haemodynamics is not clear. Objectives ... -
Chronic distress and acute vascular stress responses associated with ambulatory blood pressure in low-testosterone African men: the SABPA Study
Malan, N.T.; Hamer, M.; Schutte, A.E.; Huisman, H.W.; Schutte, R.; Smith, W.; Mels, C.M.C.; Van Rooyen, J.M.; Malan, L. (Nature Publishing Group, 2014)It is known that low testosterone (T) and high cortisol levels are associated with hypertension as well as with chronic stress, linking stress with elevated blood pressure (BP). However, the association between acute ... -
Cohort profile: sympathetic activity and ambulatory blood pressure in Africans (SABPA) prospective cohort study
Malan, Leoné; Hamer, Mark; Steyn, Hendrik S.; Malan, Nicolaas T.; Frasure-Smith, Nancy (Oxford Univ Press, 2015)Adapting to an over–demanding stressful urban environment may exhaust the psychophysiological resources to cope with these demands, and lead to sympathetic nervous system dysfunction. The evidence that an urban–dwelling ... -
Comparison of central pressure estimates obtained from SphygmoCor, Omron HEM-9000AI and carotid applanation tonometry
Kips, Jan G.; Schutte, Aletta E.; Huisman, Hugo W.; Van Rooyen, Johannes M.; Fourie, Catharina M.; Malan, Leoné; Schutte, Rudolph (Lipppincott, Williams & Wilkins, 2011)Background: The Omron HEM-9000AI is the first automated tonometer to provide an estimate of central SBP (cSBP), which is considered to be more predictive of cardiovascular events than brachial pressure. However, considerable ... -
Comparison of Telomere Length in Black and White Teachers From South Africa: the Sympathetic Activity and Ambulatory Blood Pressure in Africans Study
Von Kanel, Roland; Malan, Nicolaas Theodor; Hamer, Mark; Malan, Leoné (Lippincott Williams & Wilkins, 2015)Objective: 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 ... -
Conventional and behavioral risk factors explain differences in sub-clinical vascular disease between black and Caucasian South Africans: the SABPA study
Hamer, M.; Malan, L.; Schutte, A.E.; Huisman, H.W.; Van Rooyen, J.M.; Schutte, Rudolph; Fourie, C.M.T.; Malan, N.T.; Seedat, Y.K. (Elsevier, 2011)Conventional and behavioral risk factors explain differences in sub-clinical vascular disease between black and Caucasian South Africans: The SABPA study Objectives: There is an emerging burden of cardiovascular disease ... -
Defensive active coping facilitates chronic hyperglycaemia and endothelial dysfunction in African men: the SABPA study
Malan, L.; Hamer, M.; Steyn, H.S.; Schutte, R.; Smith, W.; Van Rooyen, J.M.; Fourie, C.M.T.; Malan, N.T. (Elsevier, 2013)Background: Dissociation between behavioural defensive active coping (AC) control albeit physiological “loss of control” responses was associated with silent ischaemia and structural wall abnormalities in African men. Whether ... -
Defensive coping and renovascular disease risk. Adrenal fatigue in a cohort of Africans and Caucasians: the SABPA study
De Kock, Andrea; Malan, Leoné; Hamer, Mark; Cockeran, Marike; Malan, Nico T. (Elsevier, 2015)Background: Defensive coping is an established cardiovascular risk factor in Africans. Additionally, chronic, excessive or inadequate hypothalamic pituitary adrenal axis (HPAA) stress responses could either increase or ... -
Defensive coping facilitated a smaller cortisol-to-estradiol ratio and a higher hypertension risk: the SABPA study
Malan, Leoné; De Kock, Andrea; Hamer, Mark; Cockeran, Marike; Malan, Nicolaas Theodor (Taylor & Francis, 2018)Objectives: Taxing psychosocial stress and defensive coping have been associated with hypoactivity in cortisol, a vasoconstrictive agent. Estradiol has vasodilatory properties with cardio- and neuroprotective effects. It ... -
Defensive coping facilitates higher blood pressure and early sub–clinical structural vascular disease via alterations in heart rate variability: the SABPA study
Malan, L.; Hamer, M.; Schutte, R.; Van Rooyen, J.M.; Mels, C.M.; Fourie, C.M.T.; Uys, A.S.; Malan, N.T. (Elsevier, 2013)Objectives: Defensive coping (AC) responses in urban African males have been associated with vascular responsiveness, partly explaining autonomic nervous system dysfunction. We therefore aimed to assess whether AC responses ... -
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
Reimann, Manja; Hamer, Mark; Malan, Nicolaas T.; Malan, Leoné; Schlaich, Markus P.; Lambert, Gavin W.; Ziemssen, Tjalf (Lippincott, Williams & Wilkins, 2013)OBJECTIVE: 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 ... -
Leukocyte telomere length and hemostatic factors in a South African cohort: the SABPA study
Von Känel, R.; Malan, N.T.; Hamer, M.; Van der Westhuizen, F.H.; Malan, L. (Wiley, 2014)Background Incident atherothrombotic disease is predicted by leukocyte telomere length, a marker of biological age, and hemostatic factor levels, indicating a hypercoagulable state. We hypothesized that shorter telomeres ... -
Low serum testosterone and increased diastolic ocular perfusion pressure: a risk for retinal microvasculature
Malan, Nico T.; Smith, Wayne; Von Känel, Roland; Hamer, Mark; Schutte, Alta E.; Malan, Leoné (Verlag Hans Huber Hogrefe Ag, 2015)Summary: Background: 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 ... -
Metabolic and glutathione redox markers associated with brain-derived neurotrophic factor in depressed African men and women: evidence for counterregulation?
Harvey, B.H.; Hamer, M.; Louw, R.; Van der Westhuizen, F.H.; Malan, L. (Karger, 2013)Background: Major depression is associated with evidence for metabolic and redox imbalance and also with reports of lower serum levels of brain-derived neurotrophic factor (BDNF). However, the relationship between these ... -
Plasma renin responses to mental stress and carotid intima-media thickness in black Africans: the SABPA study
Hamer, M.; Malan, L.; Schutte, A.E.; Huisman, H.W.; Van Rooyen, J.M.; Schutte, R.; Foirie, C.M.T.; Malan, N.T. (Nature Publishing Group, 2011)The renin–angiotensin–aldosterone system can be activated by sympathetic nervous input and is thought to have an important role in the prevalence of hypertension and cardiovascular risk in black Africans. We examined (1) ... -
Procoagulant reactivity to laboratory acute mental stress in Africans and Caucasians, and its relation to depressive symptoms: the SABPA study
Von Känel, Roland; Hamer, Mark; Malan, Nico T.; Scheepers, Kobus; Malan, Leoné (Thieme, 2013)The risk of cardiovascular disease is dramatically increasing in Africans (black). The prothrombotic stress response contributes to atherothrombotic disease and is modulated by depressive symptoms. We examined coagulation ... -
Progression of cardiovascular risk factors in black Africans: 3 year follow up of the SABPA cohort study
Hamer, Mark; Malan, Nico T.; Schutte, Alta E.; Huisman, Hugo W.; Malan, Leoné (Elsevier, 2015)Recent work identified a high prevalence of modifiable risk factors for cardiovascular disease (CVD) among urban black South Africans. The aim was to track the progression of CVD risk factors in a multi-ethnic sample of ...