A population-based study in Ghana to investigate inter-individual variation in plasma t-PA and PAI-1.

INTRODUCTION: Susceptibility to arterial thrombosis has a significant genetic component that is partly due to the expression of two proteins, tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1), that directly influence thrombus formation and degradation. We have initiated a large-scale population-based study to characterize the genetic architecture of plasma t-PA and PAI-1 in Blacks from Sunyani, Ghana. DESIGN: The design of the study is based on the recruitment of 2000 unrelated subjects who are ascertained without regard to chronic disease status. The analyses of the results will be done by dividing the data into two parts, a modeling set and a validation data set. This study design will facilitate the identification of genetic, environmental, and demographic factors that contribute to inter-individual variation in plasma levels of t-PA and PAI-1 in the population at-large. RESULTS: We report the specifics of the study design, as well as phenotype information on the first 1000 subjects. Our results show that females and males differ significantly in several key measures, including PAI-1, BMI, total cholesterol, and systolic blood pressure. CONCLUSIONS: The data collected from this population-based study demonstrate significant sex differences in PAI-1 and critical factors that may influence risk of thrombosis. These samples will serve to inform the genetic analyses of t-PA and PAI- levels.

Cardiovascular Disease Risk Factors in Ghana during the Rural-to-Urban Transition: A Cross-Sectional Study.

Populations in sub-Saharan Africa are shifting from rural to increasingly urban. Although the burden of cardiovascular disease is expected to increase with this changing landscape, few large studies have assessed a wide range of risk factors in urban and rural populations, particularly in West Africa. We conducted a cross-sectional, population-based survey of 3317 participants from Ghana (≥18 years old), of whom 2265 (57% female) were from a mid-sized city (Sunyani, population ~250,000) and 1052 (55% female) were from surrounding villages (populations <5000). We measured canonical cardiovascular disease risk factors (BMI, blood pressure, fasting glucose, lipids) and fibrinolytic markers (PAI-1 and t-PA), and assessed how their distributions and related clinical outcomes (including obesity, hypertension and diabetes) varied with urban residence and sex. Urban residence was strongly associated with obesity (OR: 7.8, 95% CI: 5.3-11.3), diabetes (OR 3.6, 95% CI: 2.3-5.7), and hypertension (OR 3.2, 95% CI: 2.6-4.0). Among the quantitative measures, most affected were total cholesterol (+0.81 standard deviations, 95% CI 0.73-0.88), LDL cholesterol (+0.89, 95% CI: 0.79-0.99), and t-PA (+0.56, 95% CI: 0.48-0.63). Triglycerides and HDL cholesterol profiles were similarly poor in both urban and rural environments, but significantly worse among rural participants after BMI-adjustment. For most of the risk factors, the strength of the association with urban residence did not vary with sex. Obesity was a major exception, with urban women at particularly high risk (26% age-standardized prevalence) compared to urban men (7%). Overall, urban residents had substantially worse cardiovascular risk profiles, with some risk factors at levels typically seen in the developed world.

Epistatic interactions in genetic regulation of t-PA and PAI-1 levels in a Ghanaian population.

The proteins, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1), act in concert to balance thrombus formation and degradation, thereby modulating the development of arterial thrombosis and excessive bleeding. PAI-1 is upregulated by the renin-angiotensin system (RAS), specifically by angiotensin II, the product of angiotensin converting enzyme (ACE) cleavage of angiotensin I, which is produced by the cleavage of angiotensinogen (AGT) by renin (REN). ACE indirectly stimulates the release of t-PA which, in turn, activates the corresponding fibrinolytic system. Single polymorphisms in these pathways have been shown to significantly impact plasma levels of t-PA and PAI-1 differently in Ghanaian males and females. Here we explore the involvement of epistatic interactions between the same polymorphisms in central genes of the RAS and fibrinolytic systems on plasma t-PA and PAI-1 levels within the same population (n = 992). Statistical modeling of pairwise interactions was done using two-way ANOVA between polymorphisms in the ETNK2, RENIN, ACE, PAI-1, t-PA, and AGT genes. The most significant interactions that associated with t-PA levels were between the ETNK2 A6135G and the REN T9435C polymorphisms in females (p = 0.006) and the REN T9435C and the TPA I/D polymorphisms (p = 0.005) in males. The most significant interactions for PAI-1 levels were with REN T9435C and the TPA I/D polymorphisms (p = 0.001) in females, and the association of REN G6567T with the TPA I/D polymorphisms (p = 0.032) in males. Our results provide evidence for multiple genetic effects that may not be detected using single SNP analysis. Because t-PA and PAI-1 have been implicated in cardiovascular disease these results support the idea that the genetic architecture of cardiovascular disease is complex. Therefore, it is necessary to consider the relationship between interacting polymorphisms of pathway specific genes that predict t-PA and PAI-1 levels.

A comparative analysis of perceived stigma among HIV-positive Ghanaian and African American males.

The purpose of this paper was to address two questions: (i) Do Ghanaian and African American males with HIV/AIDS experience different types and degrees of stigma? and (ii) Is the impact of stigma associated with HIV/AIDS on the self different for Ghanaian and African American males? A quantitative method was used, and the four dimensions of stigma (social rejection, financial insecurity, internalised shame, and social interaction) were identified and measured using combination Likert-type questionnaires. Data regarding positive feelings of self-worth and self-deprecation, stress related to body image, and personal control were also collected in Ghana and the southeastern USA. The sample consisted of 55 men from Ghana and 55 men from the southeastern USA. Results indicate that values for the scales measuring stigma and self-perception were significantly higher for the Ghanaian sample than for the African American sample. Thus we conclude that the Ghanaian sample living with HIV/AIDS experienced a greater amount of negative self-perception and stigma-related strife than the African American sample.