The angiotensin-converting enzyme insertion/deletion polymorphism and its associations with carotid artery wall thickness and coronary heart disease: The atherosclerosis risk in communities study

Coronary heart disease (CHD) is the leading cause of death in the United States. Recently, renin-angiotensin system (RAS) was found associated with atherosclerosis formation, with angiotensin II inducing vascular smooth muscle cell growth and migration, platelet activation and aggregation, and stimulation of plasminogen activator inhibitor-1. Angiotensin II is converted from angiotensin I by angiotensin I-converting enzyme (ACE) and this enzyme is mainly genetically determined. The ACE gene has been assigned to chromosome 17q23 and an insertion/deletion (I/D)polymorphism has been characterized by the presence/absence of a 287 bp fragment in intron 16 of the gene. The two alleles form three genotypes, namely, DD, ID and II and the DD genotype has been linked to higher plasma ACE levels and cell ACE activity.^ In this study, the association between the ACE I/D polymorphism and carotid artery wall thickness measured by B-mode ultrasound was investigated in a biracial sample, and the association between the gene and incident CHD was investigated in whites and if the gene-CHD association in whites, if any, was due to the gene effect on atherosclerosis. The study participants are from the prospective Atherosclerosis Risk in Communities (ARIC) Study, including adults aged 45 to 65 years. The present dissertation used a matched case-control design for studying the associations of the ACE gene with carotid artery atherosclerosis and an unmatched case-control design for the association of the gene with CHD. A significant recessive effect of the D allele on carotid artery thickness was found in blacks (OR = 3.06, 95% C.I: 1.11-8.47, DD vs. ID and II) adjusting for age, gender, cigarette smoking, LDL-cholesterol and diabetes. No similar associations were found in whites. The ACE I/D polymorphism is significantly associated with coronary heart disease in whites, and while stratifying data by carotid artery wall thickness, the significant associations were only observed in thin-walled subgroups. Assuming a recessive effect of the D allele, odds ratio was 2.84 (95% C.I:1.17-6.90, DD vs. ID and II) and it was 2.30 (95% C.I:1.22-4.35, DD vs. ID vs. II) assuming a codominant effect of the D allele. No significant associations were observed while comparing thick-walled CHD cases with thin-walled controls. Following conclusions could be drawn: (1) The ACE I/D polymorphism is unlikely to confer appreciable increase in the risk of carotid atherosclerosis in US whites, but may increases the risk of carotid atherosclerosis in blacks. (2) ACE I/D polymorphism is a genetic risk factor for incident CHD in US whites and this effect is separate from the chronic process of atherosclerosis development. Finally, the associations observed here are not causal, since the I/D polymorphism is in an intron, where no ACE proteins are encoded. ^

The illness experiences of patients and their family members living with congestive heart failure

Purpose. To investigate and understand the illness experiences of patients and their family members living with congestive heart failure (CHF). ^ Design. Focused ethnographic design. ^ Setting. One outpatient cardiology clinic, two outpatient heart failure clinics, and informants' homes in a large metropolitan city located in southeast Texas. ^ Sample. A purposeful sampling technique was used to select a sample of 28 informants. The following somewhat overlapping, sampling strategies were used to implement the purposeful method: criterion; typical case; operational construct; maximum variation; atypical case; opportunistic; and confirming and disconfirming case sampling. ^ Methods. Naturalistic inquiry consisted of data collected from observations, participant observations, and interviews. Open-ended semi-structured illness narrative interviews included questions designed to elicit informant's explanatory models of the illness, which served as a synthesizing framework for the analysis. A thematic analysis process was conducted through domain analysis and construction of data into themes and sub-themes. Credibility was enhanced through informant verification and a process of peer debriefing. ^ Findings. Thematic analysis revealed that patients and their family members living with CHF experience a process of disruption, incoherence, and reconciling. Reconciling emerged as the salient experience described by informants. Sub-themes of reconciling that emerged from the analysis included: struggling; participating in partnerships; finding purpose and meaning in the illness experience; and surrendering. ^ Conclusions. Understanding the experiences described in this study allows for a better understanding of living with CHF in everyday life. Findings from this study suggest that the experience of living with CHF entails more than the medical story can tell. It is important for nurses and other providers to understand the experiences of this population in order to develop appropriate treatment plans in a successful practitioner-patient partnership. ^

Examining seasonal variations in physical activity among low-income Hispanic walk-trail users living in the Cameron Park Colonia

This study examines variations in physical activity by season, and within seasons by age and gender among park users living in the Cameron Park Colonia, a low-income Hispanic community along the Texas-Mexico border. This is the first study of its kind to evaluate seasonal variations by physical activity among a Hispanic population. We hypothesized that (1) there are no differences in overall physical activity by season; (2) youth engage in more sport-related physical activity compared to adults, (3) males engage in more physical activity than females, and (4) there are differences in physical activity between walk-trail users compared to non walk-trail users in the park.^ Physical activity behavioral data was collected (males n=2,093; females n=1,014) at two time periods (winter 2007; summer 2007) via direct observations and assessed park use, walking trail use, and physical activity (moderate-to-vigorous physical activity (MVPA) by seasons. Frequencies for physical activities were calculated for gender, age groups, and season. Separate Pearson's chi-square analyses were used to address variations in physical activity, age, gender, intensity level of physical activity by season, between walk-trails users and non walk-trail users.^ People visiting the park engaged in more sedentary behavior in winter than summer and a higher percentage engaged in MVPA in the summer than winter (p<.05). More females engaged in light activity compared to males (p<.05). Walk-trail users consisted mostly of females and engaged in more light activity than non walk-trail users (p<.05) who participated in more MVPA.^ Increasing access to parks and walk-trails may be an intervention strategy to increase physical activity among Hispanics. More research is needed to assess promoting trail use and determining long-term effects on physical activity among minority/ethnic groups at greater risk of a sedentary lifestyle and reasons for trail use and non-use. Future studies should focus on the types of activities Hispanics engage in at different parks particularly between men and women. As a result of this study city officials and planners may use this information to build and design parks that cater to the types of activities that Hispanics engage in and may use to meet physical activity guidelines.^