4,847 research outputs found
Twenty-Five Year Secular Trends in Lipids and Modifiable Risk Factors in a Population-Based Biracial Cohort: The Coronary Artery Risk Development in Young Adults (CARDIA) Study, 1985-2011
BACKGROUND: Cross-sectional analyses suggest that total and low-density lipoprotein cholesterol (LDL-c) trends that had been declining are now reversing. We examined longitudinal data from the Coronary Artery Risk Development in Young Adults (CARDIA) study to examine secular trends in total cholesterol, LDL-c, high-density lipoprotein cholesterol (HDL-c), and triglycerides over 25 years. We also assessed whether modifiable lifestyle factors (body mass index, physical activity, alcohol consumption, smoking, and lipid-lowering medications) are associated with these trends.
METHODS AND RESULTS: CARDIA recruited 5115 black and white men and women ages 18 to 30 years from 4 US communities in 1985-1986, and re-examined them 5, 10, 15, 20, and 25 years later. Secular trends, modeled as age-matched time trends, were estimated using repeated-measures regression stratified on race and sex. Total cholesterol and LDL-c initially decreased approximately 5 to 8 mg/dL between visits before plateauing and moving toward adverse trends in all groups, except black women, by year 25. HDL-c showed an upward secular trend of 1 to 3 mg/dL between visits starting at year 15 in all groups; triglyceride trends were largely flat. Obesity and use of lipid-lowering medications, which both increased over follow-up, had strong independent, but opposite, associations with lipid trends over time. In aggregate, associations of modifiable lifestyle factors counterbalanced one another, minimally influencing secular trends.
CONCLUSIONS: Over 25 years, initially favorable trends in total cholesterol and LDL-c have leveled off and may be reversing, persisting after control for modifiable risk factors. Factors such as dietary changes over 25 years and poor adherence to medications are candidates for additional investigation
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Diurnal blood pressure pattern and development of prehypertension or hypertension in young adults: the CARDIA study
Nondippers (people whose sleep systolic blood pressure [SBP] fails to decrease >10% from daytime SBP) have increased risk of cardiovascular disease. The prevalence of nondipping in younger adults has not been well studied, nor has its value for predicting hypertension. We examined the prevalence of nondipping in a substudy of the Coronary Artery Risk Development in Young Adults (CARDIA) Study. We used Cox regression to estimate the hazard ratio (HR) conferred by nondipping for incident prehypertension or hypertension (preHTN/HTN) over 15 years. Of the 264 nonhypertensive participants at baseline, 118 (45%) were nondippers. Blacks were more likely than whites to be nondippers (52% versus 33%, P = .004). The incidence rate of preHTN/HTN was 29.2/1000 person-years among dippers and 36.2/1000 person-years among nondippers. Compared with those in the lowest quartile of nighttime to daytime SBP, those in the highest quartile were more likely to develop preHTN/HTN (HR 1.61; P = .06), but this relationship was attenuated after adjustment (HR 1.34; P = .27). Our results demonstrate that nondipping is common in young, nonhypertensive adults, and is more common in blacks than whites. Nondipping might predate a meaningful clinically detected increase in BP in some people, but more research in larger study samples is needed
Fluoromycobacteriophages for rapid, specific, and sensitive antibiotic susceptibility testing of Mycobacterium tuberculosis
Rapid antibiotic susceptibility testing of Mycobacterium tuberculosis is of paramount importance as multiple- and extensively- drug resistant strains of M. tuberculosis emerge and spread. We describe here a virus-based assay in which fluoromycobacteriophages are used to deliver a GFP or ZsYellow fluorescent marker gene to M. tuberculosis, which can then be monitored by fluorescent detection approaches including fluorescent microscopy and flow cytometry. Pre-clinical evaluations show that addition of either Rifampicin or Streptomycin at the time of phage addition obliterates fluorescence in susceptible cells but not in isogenic resistant bacteria enabling drug sensitivity determination in less than 24 hours. Detection requires no substrate addition, fewer than 100 cells can be identified, and resistant bacteria can be detected within mixed populations. Fluorescence withstands fixation by paraformaldehyde providing enhanced biosafety for testing MDR-TB and XDR-TB infections. © 2009 Piuri et al
Fine Particulate Air Pollution and the Progression of Carotid Intima-Medial Thickness: A Prospective Cohort Study from the Multi-Ethnic Study of Atherosclerosis and Air Pollution
Background
Fine particulate matter (PM2.5) has been linked to cardiovascular disease, possibly via accelerated atherosclerosis. We examined associations between the progression of the intima-medial thickness (IMT) of the common carotid artery, as an indicator of atherosclerosis, and long-term PM2.5 concentrations in participants from the Multi-Ethnic Study of Atherosclerosis (MESA).
Methods and Results
MESA, a prospective cohort study, enrolled 6,814 participants at the baseline exam (2000–2002), with 5,660 (83%) of those participants completing two ultrasound examinations between 2000 and 2005 (mean follow-up: 2.5 years). PM2.5 was estimated over the year preceding baseline and between ultrasounds using a spatio-temporal model. Cross-sectional and longitudinal associations were examined using mixed models adjusted for confounders including age, sex, race/ethnicity, smoking, and socio-economic indicators. Among 5,362 participants (5% of participants had missing data) with a mean annual progression of 14 µm/y, 2.5 µg/m3 higher levels of residential PM2.5 during the follow-up period were associated with 5.0 µm/y (95% CI 2.6 to 7.4 µm/y) greater IMT progressions among persons in the same metropolitan area. Although significant associations were not found with IMT progression without adjustment for metropolitan area (0.4 µm/y [95% CI −0.4 to 1.2 µm/y] per 2.5 µg/m3), all of the six areas showed positive associations. Greater reductions in PM2.5 over follow-up for a fixed baseline PM2.5 were also associated with slowed IMT progression (−2.8 µm/y [95% CI −1.6 to −3.9 µm/y] per 1 µg/m3 reduction). Study limitations include the use of a surrogate measure of atherosclerosis, some loss to follow-up, and the lack of estimates for air pollution concentrations prior to 1999.
Conclusions
This early analysis from MESA suggests that higher long-term PM2.5 concentrations are associated with increased IMT progression and that greater reductions in PM2.5 are related to slower IMT progression. These findings, even over a relatively short follow-up period, add to the limited literature on air pollution and the progression of atherosclerotic processes in humans. If confirmed by future analyses of the full 10 years of follow-up in this cohort, these findings will help to explain associations between long-term PM2.5 concentrations and clinical cardiovascular events.
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Spin-Peierls transitions in magnetic donor-acceptor compounds of tetrathiafulvalene (TTF) with bisdithiolene metal complexes
The spin-Peierls transition is considered as a progressive spin-lattice dimerization occurring below a transition temperature in a system of one-dimensional antiferromagnetic Heisenberg chains. In the simplest theories, the transition is second order and the ground state is a singlet with a magnetic gap. The historical origins and theoretical development of the concept are examined. Magnetic susceptibility and EPR measurements on the π-donor-acceptor compounds TTF·MS4C4(CF3)4 (M=Cu, Au; TTF is tetrathiafulvalene) are reported. These compounds exhibit clearly the characteristics of the spin-Peierls transition in reasonably good agreement with a mean-field theory. The susceptibility of each compound has a broad maximum near 50 K, while the transitions occur at 12 and 2.1 K for M=Cu and Au, respectively. EPR linewidth observations over a broad temperature range are examined. Areas for further experimental and theoretical work are indicated, and a critical comparison is made of related observations on other materials
Associations of the Local Food Environment with Diet Quality—A Comparison of
There is growing interest in understanding how food environments affect diet, but characterizing the food environment is challenging. The authors investigated the relation between global diet measures (an empirically derived "fats and processed meats" (FPM) dietary pattern and the Alternate Healthy Eating Index (AHEI)) and three complementary measures of the local food environment: 1) supermarket density, 2) participant-reported assessments, and 3) aggregated survey responses of independent informants. Data were derived from the baseline examination (2000–2002) of the Multi-Ethnic Study of Atherosclerosis, a US study of adults aged 45–84 years. A healthy diet was defined as scoring in the top or bottom quintile of AHEI or FPM, respectively. The probability of having a healthy diet was modeled by each environment measure using binomial regression. Participants with no supermarkets near their homes were 25–46% less likely to have a healthy diet than those with the most stores, after adjustment for age, sex, race/ethnicity, and socioeconomic indicators: The relative probability of a healthy diet for the lowest store density category versus the highest was 0.75 (95% confidence interval: 0.59, 0.95) for the AHEI and 0.54 (95% confidence interval: 0.42, 0.70) for FPM. Similarly, participants living in areas with the worst-ranked food environments (by participants or informants) were 22–35% less likely to have a healthy diet than those in the best-ranked food environments. Efforts to improve diet may benefit from combining individual and environmental approaches.http://deepblue.lib.umich.edu/bitstream/2027.42/58345/1/Associations of the local food environment with diet quality - A comparison of Assessments based on surveys .pd
Observation of a Spin-Peierls Transition in a Heisenberg Antiferromagnetic Linear-Chain System
Magnetic-susceptibility and EPR measurements are reported which provide the first unambiguous evidence for a spin-Peierls transition in a system of linear one-dimensional antiferromagnetic Heisenberg chains. The material studied is TTFCuS4C4(CF3)4 (TFF stands for tetrathiafulvalinium). At 12 K, the spin-lattice system undergoes a second-order phase transition to a singlet ground state
Metabolic syndrome and risk of venous thromboembolism: Longitudinal Investigation of Thromboembolism Etiology
In a recent case-control study, the odds of metabolic syndrome (MetSyn) among deep vein thrombosis cases was almost twice the odds as among controls. We tested the hypothesis that the incidence of non-cancer-related venous thromboembolism (VTE) is higher among adults with MetSyn and further, that associations are stronger for idiopathic than secondary VTE
Thermal and magnetic study of exchange in the quasi-1-D molecular compound, TTFâ‹…PtS\u3csub\u3e4\u3c/sub\u3eC\u3csub\u3e4\u3c/sub\u3e(CF\u3csub\u3e3\u3c/sub\u3e)\u3csub\u3e4\u3c/sub\u3e
Single crystalmagnetic susceptibility results from 2.5 K to 270 K and specific heat results from 3 K to 16 K are reported for TTF⋅PtS4C4(CF3)4, (TTF=tetrathiafulvalene). The combined results are analyzed using a simple model which ignores differences between the two types of S=1/2 spin carriers and involves a system of ferromagnetic chains treated ’’exactly’’, with interchain antiferromagnetic interaction evaluated in a mean field approximation. Above an apparent ordering transition at 8 K, the susceptibility is well described by the model irrespective of whether the ferromagnetic exchange is Heisenberg, Ising or intermediate to these. The magnetic contribution to the specific heat is obtained using earlier results for the isostructural Au compound. Comparison with specific heat calculations for the Heisenberg, Ising and intermediate cases successfully narrows the ambiguity to an intermediate anisotropic exchange close to the Heisenberg limit
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