Life-style factors and risk for abdominal aortic aneurysm in a cohort of Finnish male smokers

Viruses as the causative agent related to 'dampness' and the missing link between allergen exposure and onset of allergic disease

Asthma and asthma-like symptoms occur more often among people living in humid indoor climates. It has been postulated that the higher concentration of allergens in these environments is the cause for the increase in the number of affected people. However, poor correlations between allergen concentration and symptoms indicate a missing link between allergen exposure and onset of asthma. Respiratory viruses have been identified in up to 85% cases of asthma or exacerbations of asthma. The missing link between respiratory diseases and humid indoor climates could therefore be attributed to viruses. The infectious effectiveness of respiratory viruses depends strongly on the environment where the viruses are spread. For respiratory viruses, survival and infectivity are dependent on temperature and relative humidity. A direct link between virus-induced inflammation and the asthmatogenic process has been proposed. Therefore, a more effective spreading of viral infections in damp indoor climates is likely to represent the main cause for the increased prevalence of asthma in these environments. Moreover, the incidence of viral infections is higher in patients with asthma compared with that in control subjects. Therefore, a humid indoor climate could also represent a higher risk for persons already sensitized to one or more allergens.

PRACTICAL IMPLICATIONS

In epidemiological studies where the relationship between moisture in the indoor climate, respiratory symptoms and exposure to allergens is investigated it will be necessary to analyze the role of respiratory viruses in relation to respiratory symptoms. Today, the necessary techniques to address the presence of viruses [e.g. polymerase chain reaction (PCR), antibodies] are highly sensitive. In order to further our understanding of why the frequency of asthma and atopic diseases is still increasing, it is mandatory to implement these methods.

Risk factors associated with abdominal aortic aneurysm: a population-based study with historical and current data

OBJECTIVES

To define risk factors associated with the development of abdominal aortic aneurysm (AAA) in a population-based case-control study.

MATERIAL AND METHODS

Thirty-five patients found to have AAA at screening were compared with 140 age- and sex-matched controls. Three distinct comparisons were made. Current risk factors in both cohorts were compared. Because data were also available for both cohorts from a study conducted 12 years previously, a historical comparison was made between risk factors identified at the time of this initial evaluation. A longitudinal comparison was made between historical and current risk factors.

RESULTS

Elevated low-density-lipoprotein cholesterol, total cholesterol, and triglyceride levels 12 years before AAA screening were associated with current AAA with an odds ratio (OR) of 2.3 (95% confidence interval [CI], 1.2 to 4.4); OR, 1.9 (95% CI, 1.3 to 2.8); and OR, 1.9 (95% CI,1.2 to 3.1)/mmol/L, respectively. Current variables assessed at AAA screening that were associated with AAA were: A history of atherosclerotic disease, OR, 3.8 (95% CI, 1.7 to 8.5); having a first-degree relative with AAA, OR, 4.4 (95% CI, 1.5 to 13.0); current smoking, OR, 5.2 (95% CI, 1.6 to 16.8); high-density-lipoprotein cholesterol level, OR, 0.1 (95% CI, 0.02 to 0.7)/mmol/L; and high-sensitivity C-reactive protein (hsCRP) level, OR, 1.1 (95% CI, 1.01 to 1.2)/mg/L. Hypertension and diabetes were not associated with AAA. A significant increase of hsCRP over time (12 years) was observed in AAA patients ( P = .039) but not among controls. The variables of a history of atherosclerosis, smoking, and family history of AAA appear to interact synergistically to increase the prevalence of AAA ( P < .001).

CONCLUSION

Among traditional risk factors for atherosclerosis, some were associated with AAA and others were not, indicating complex and partly different causes. Inflammation and heredity appear to be important factors in the development of AAA.

Adaptation of the endothelium to fluid flow: in vitro analyses of gene expression and in vivo implications

Biomechanical forces generated by blood flow play an important role in the pathogenesis of vascular disease. For example, regions exposed to non-uniform shear stresses develop early atherosclerotic lesions while areas exposed to uniform shear stresses are protected. A variety of in vitro flow apparatuses have been created to apply well-characterized flow patterns to endothelial cells in an effort to dissect the cellular and molecular pathways involved in these distinct processes. Recent advances in biotechnology have permitted large-scale transcriptional profiling techniques to replace candidate gene screens and have allowed the genome-wide examination of biomechanical force-induced endothelial gene expression profiles. This review provides an overview of biomechanical force-induced modulation of endothelial phenotype. It examines the effect of sustained laminar shear stress (LSS), a type of uniform shear stress, on in vitro endothelial gene expression by synthesizing data from the early candidate gene and differential display polymerase chain reaction (PCR) approaches to the numerous, recent, high throughput functional genomic analyses. These studies demonstrate that prolonged LSS regulates the expression of only a small percentage (approximately 1-5%) of endothelial genes, and this transcriptional profile produces an endothelial phenotype that is quiescent, being protected from apoptosis, inflammation and oxidative stress. These observations provide a possible molecular mechanism for the strong correlation between patterns of blood flow and the occurrence of vascular pathologies, such as atherosclerosis, in vivo.

From 1989 to 2001: what have we learned about the "biological actions of beta-carotene"?

Dr. James Allen Olson helped us to define the role of beta-carotene in human health by categorizing these as "functions, actions and associations." In the last decade, significant research has shown that beta-carotene acts as an antioxidant in biologically relevant systems, affects several aspects of human immune function and higher intake/serum levels are associated with improvements in certain physiological functions such as lung function. The unexpected findings of increased lung cancer in beta-carotene supplemented smokers in the ATBC and CARET intervention studies have resulted in the need for expanded research efforts to define the mechanism(s) of action of beta-carotene. Recent survey data as well as laboratory animal studies continue to find an inverse association between beta-carotene and cancer risk. Because beta-carotene is the major source of vitamin A for the majority of the world's population, it is critical to define the safe levels of intake from foods and supplements.

Influence of smoking on predictors of vascular disease

Beyond the already well-established strong causative relationship with cancer, smoking increases the risk for vascular disease. Smoking may act directly or adversely influence risk factors contributing to the development of vascular disease. Smoking causes endothelial dysfunction, dyslipidemia (decreased high-density lipoprotein cholesterol levels, hypertriglyceridemia and increased oxidation of low-density lipoprotein cholesterol) and platelet activation leading to a prothrombotic state. Smoking increases emerging risk factors (eg, fibrinogen, homocysteine, and high-sensitivity C-reactive protein) and increases insulin resistance and the risk of developing type 2 diabetes mellitus. The beneficial effects of statins and antioxidants (eg, vitamins C and E, beta-carotene) are counteracted by smoking. Smoking-induced alterations in growth factors, adhesion molecules, and even in genes can accelerate the progression of atherosclerosis. The aim of this review is to consider the adverse consequences of smoking on the factors predisposing to vascular disease and to emphasize the beneficial effects of smoking cessation.

Persistent increase in the incidence of abdominal aortic aneurysm in Scotland, 1981–2000

Background

In the 1970s and 1980s, mortality and morbidity rates for abdominal aortic aneurysm (AAA) increased throughout the developed world. As AAAs are associated with similar risk factors to other cardiovascular diseases that have recently decreased in incidence, the incidence of AAA should show a similar declining trend.

Methods

Routinely collected data were obtained on all primary diagnoses of aortic aneurysm resulting in death or hospital discharge in Scotland between 1981 and 2000. Trends in the data were analysed according to sex and age, aneurysm site and type of hospital admission.

Results

Between 1981 and 2000, 42·3 per cent of the 10 822 deaths from aortic aneurysm in Scotland were attributed to the abdominal aorta. Age-adjusted mortality rates for AAA increased 2·6-fold from 2·62 deaths per 100 000 in 1981 to 6·82 per 100 000 in 2000. Hospital admissions for AAA also rose threefold, with increases in both elective admissions (from 3·05 to 7·80 per 100 000) and emergency admissions (from 7·44 to 11·23 per 100 000).

Conclusion

The incidence of AAA has increased over the past 20 years in Scotland. This is unlikely to be due simply to changes in detection and diagnosis, data inaccuracies, coding or ageing of the population. The incidence of both elective and emergency admission for AAA increased, suggesting that a genuine and persistent rise in the incidence of AAA has probably occurred.

Epidemiology of smoking-induced cardiovascular disease

Cigarette smoking is a major cause of coronary heart disease, stroke, aortic aneurysm, and peripheral vascular disease. The risk is manifest both as an increased risk for thrombosis of narrowed vessels and as an increased degree of atherosclerosis in those vessels. The cardiovascular risks owing to cigarette smoking increase with the amount smoked and with the duration of smoking. Risks are not reduced by smoking cigarettes with lower machine-measured yields of tar and nicotine, but those who have only smoked pipes or cigars seem to have a lower risk for cardiovascular diseases. Cessation of cigarette smoking reduces disease risks, although risks may remain elevated for a decade or more after cessation.