MOTIVATION: The increasing prevalence of metabolic syndrome (MetS) is creating
immense concern worldwide. In 2009, the International Diabetes Federation (IDF)
announced the new MetS definition. MetS is diagnosed by any 3 of the following 5
indicators being present: increased waist circumference (WC), blood pressure (BP),
triglycerides, and fasting glucose values, and decreased high–density lipoprotein
cholesterol (HDL–C) concentrations. Psychosocial stress relating to an urban
environment or acculturation greatly influences the prevalence of both MetS and target
organ damage (TOD). Furthermore, in urban Africans, active coping (AC) responses
have been associated more with MetS and the related cardiovascular pathology than
avoidance. A further synergistic effect of MetS and AC responses was also revealed in
African men, in strong association with both subclinical atherosclerosis and renal
impairment. Microalbuminuria was four times higher in Africans with MetS, than in
those without any MetS indicators. Furthermore, Africans, especially those utilising AC
responses, present with greater carotid intima–media thickness (CIMT) than their
Caucasian counterparts, although they exhibit a lipid profile that is anti–atherogenic.
OBJECTIVES: The objectives were firstly to indicate and compare differences
regarding AC responses in the African and Caucasian men, in accord with the
prevalence of MetS indicators. Secondly, the extent to which AC responses and MetS
indicators predict endothelial dysfunction was investigated. METHODOLOGY: This comparative target population study is nested in the
Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study, which
was conducted from February until the end of May in both 2008 (Africans) and 2009
(Caucasians), avoiding seasonal changes. The Ethics Committee of the North–West
University approved the study, and all volunteers gave written informed consent prior to
participation. Procedures were conducted according to the institutional guidelines of
the Declaration of Helsinki. The participants included 202 male teachers of which 101
were African and 101 Caucasian. Ambulatory blood pressure (BP) measurements
were recorded with the Cardiotens CE120 at 30 minute intervals during the day and
60 minutes at night. Actical accelerometers determined physical activity (PA).
Registered clinical psychologists supervised completion of the psychosocial
questionnaires, including the Coping Strategy Indicator. Participants fasted overnight;
after the last BP recording, disconnection of the Cardiotens CE120 and Actical
followed. A fasting 8 hour overnight collected urine sample was obtained from each
participant. Anthropometric measurements followed, after which a registered nurse
commenced blood sampling. The SonoSite Micromaxx was used for the scanning of
CIMT. MetS indicators (glucose, triglyceride, and HDL–C), together with gamma
glutamyl transferase, cotinine, and ultrahigh–sensitivity C–reactive protein (hs–CRP),
were analyzed with Konelab 20i. The albumin–to–creatinine ratio and CIMT
determined TOD. Participants were stratified according to ethnicity and median splits
of AC response scores (high AC and low AC). Diabetic medication users (n= 8), and
participants with renal impairment (n= 2) or HIV positive (n= 13), were excluded from
analyses. 2×2 ANCOVA’s determined significant interactions for ethnicity and AC.
Partial correlations between MetS indicators and TOD were performed within each
ethnic and AC group, independent of age, alcohol consumption and PA. Regression
analyses were performed for four models, firstly with microalbuminuria and secondly with CIMT as dependent variables. Significant values were noted as p 0.05, r 0.35,
and adjusted R2 0.25.
RESULTS: Caucasian men were physically more active than African men, whilst BP,
alcohol consumption and hs–CRP levels were significantly higher in African men.
Psychological variables revealed higher avoidance scores in Caucasian men and
higher social support scores in African men. More MetS indicators exceeded the IDF
cut–off points in high AC African men (14.71%) than in their Caucasian counterparts
(3.33%). Furthermore, more MetS indicators predicted endothelial dysfunction in
African men, especially the high AC responders.
CONCLUSION: The following hypotheses were accepted: high AC responses in urban
African men were associated with a higher prevalence of MetS indicators than in their
Caucasian counterparts, while MetS indicators were associated with a marker of TOD
in urban high AC African men, but not in their Caucasian counterparts. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2011.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/4736 |
| Date | January 2010 |
| Creators | De Kock, Andrea |
| Publisher | North-West University |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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