295 research outputs found

    PGI21 Cost-Effectiveness of Peginterferon and Ribavirin for Elderly Patients with Chronic Hepatitis C: Results Based on the Nationwide Hepatitis Registration in Japan

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    Estimating forest structure in a tropical forest using field measurements, a synthetic model and discrete return lidar data

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    Tropical forests are huge reservoirs of terrestrial carbon and are experiencing rapid degradation and deforestation. Understanding forest structure proves vital in accurately estimating both forest biomass and also the natural disturbances and remote sensing is an essential method for quantification of forest properties and structure in the tropics. Our objective is to examine canopy vegetation profiles formulated from discrete return LIght Detection And Ranging (lidar) data and examine their usefulness in estimating forest structural parameters measured during a field campaign. We developed a modeling procedure that utilized hypothetical stand characteristics to examine lidar profiles. In essence, this is a simple method to further enhance shape characteristics from the lidar profile. In this paper we report the results comparing field data collected at La Selva, Costa Rica (10° 26′ N, 83° 59′ W) and forest structure and parameters calculated from vegetation height profiles and forest structural modeling. We developed multiple regression models for each measured forest biometric property using forward stepwise variable selection that used Bayesian information criteria (BIC) as selection criteria. Among measures of forest structure, ranging from tree lateral density, diameter at breast height, and crown geometry, we found strong relationships with lidar canopy vegetation profile parameters. Metrics developed from lidar that were indicators of height of canopy were not significant in estimating plot biomass (p-value = 0.31, r2 = 0.17), but parameters from our synthetic forest model were found to be significant for estimating many of the forest structural properties, such as mean trunk diameter (p-value = 0.004, r2 = 0.51) and tree density (p-value = 0.002, r2 = 0.43). We were also able to develop a significant model relating lidar profiles to basal area (p-value = 0.003, r2 = 0.43). Use of the full lidar profile provided additional avenues for the prediction of field based forest measure parameters. Our synthetic canopy model provides a novel method for examining lidar metrics by developing a look-up table of profiles that determine profile shape, depth, and height. We suggest that the use of metrics indicating canopy height derived from lidar are limited in understanding biomass in a forest with little variation across the landscape and that there are many parameters that may be gleaned by lidar data that inform on forest biometric properties

    The association of reduced lung function with blood pressure variability in African Americans: data from the Jackson Heart Study

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    Background African Americans (AAs) have lower lung function, higher blood pressure variability (BPV) and increased risk for hypertension and cardiovascular disease (CVD) compared with whites. The mechanism through which reduced lung-function is associated with increased CVD risk is unclear. Methods We evaluated the association between percent predicted lung-function and 24-hour BPV in 1008 AAs enrolled in the Jackson Heart Study who underwent ambulatory blood pressure (BP) monitoring. Lung-function was assessed as forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and the ratio of FEV1-to-FVC during a pulmonary function test using a dry rolling sealed spirometer and grouped into gender-specific quartiles. The pairwise associations of these three lung-function measures with two measures of 24-hour BPV, (1) day-night standard deviation (SDdn) and (2) average real variability (ARV) were examined for systolic BP (SBP) and, separately, diastolic BP (DBP). Results SDdn of SBP was not associated with FEV1 (mean ± standard deviation from lowest-to-highest quartile: 9.5 ± 2.5, 9.4 ± 2.4, 9.1 ± 2.3, 9.3 ± 2.6; p-trend = 0.111). After age and sex adjustment, the difference in SDdn of SBP was 0.0 (95 % CI −0.4,0.4), −0.4 (95 % CI −0.8,0.1) and −0.3 (95 % CI −0.7,0.1) in the three progressively higher versus lowest quartiles of FEV1 (p-trend = 0.041). Differences in SDdn of SBP across FEV1 quartiles were not statistically significant after further multivariable adjustment. After multivariable adjustment, no association was present between FEV1 and ARV of SBP or SDdn and ARV of DBP or when evaluating the association of FVC and FEV1-to-FVC with 24-hour BPV. Conclusion Lung-function was not associated with increased 24-hour BPV

    The Utility of Ambulatory Blood Pressure Monitoring for Diagnosing White Coat Hypertension in Older Adults

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    The beneficial effect of antihypertensive medication on reducing the risk of cardiovascular disease (CVD) events is supported by data from randomized controlled trials of older adults with hypertension. However, in clinical practice, overtreatment of hypertension in older adults may lead to side effects and an increased risk of falls. The diagnosis and treatment of hypertension is primarily based on blood pressure measurements obtained in the clinic setting. Ambulatory blood pressure monitoring (ABPM) complements clinic blood pressure by measuring blood pressure in the out-of-clinic setting. ABPM can be used to identify white coat hypertension, defined as elevated clinic blood pressure and non-elevated ambulatory blood pressure. White coat hypertension is common in older adults but does not appear to be associated with an increased risk of CVD events among this population. Herein, we review the current literature on ABPM in the diagnoses of white coat hypertension in older adults, including its potential role in preventing overtreatment

    Evaluation of Criteria to Detect Masked Hypertension

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    The prevalence of masked hypertension, out-of-clinic daytime systolic/diastolic blood pressure (SBP/DBP)≥135/85 mmHg on ambulatory blood pressure monitoring (ABPM) among adults with clinic SBP/DBP<140/90 mmHg, is high. It is unclear who should be screened for masked hypertension. We derived a clinic blood pressure (CBP) index to identify populations for masked hypertension screening. Index cut-points corresponding to 75% to 99% sensitivity and prehypertension were evaluated as ABPM testing criterion. In a derivation cohort (n=695), the index was clinic SBP+1.3*clinic DBP. In an external validation cohort (n=675), the sensitivity for masked hypertension using an index ≥190 mmHg and ≥217 mmHg and prehypertension status was 98.5%, 71.5% and 82.5%, respectively. Using NHANES data (n=11,778), we estimated that these thresholds would refer 118.6, 44.4 and 59.3 million US adults, respectively, to ABPM screening for masked hypertension. In conclusion, the CBP index provides a useful approach to identify candidates for masked hypertension screening using ABPM

    Differences in night-time and daytime ambulatory blood pressure when diurnal periods are defined by self-report, fixed-times, and actigraphy: Improving the Detection of Hypertension study

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    To determine whether defining diurnal periods by self-report, fixed-time or actigraphy produce different estimates of nighttime and daytime ambulatory blood pressure (ABP)

    Sedentary behavior and subclinical atherosclerosis in African Americans: cross-sectional analysis of the Jackson heart study

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    BACKGROUND: Previous studies have reported conflicting results as to whether an association exists between sedentary time and cardiovascular disease (CVD) risk among African Americans. These studies, however, were limited by lack of consideration of sedentary behavior in leisure versus non-leisure settings. To elucidate this relation, we investigated the associations of television (TV) viewing time and occupational sitting with carotid intima-media thickness (CIMT), a subclinical atherosclerosis measure, in a community-based sample of African Americans. METHODS: We studied 3410 participants from the Jackson Heart Study, a single-site, community-based study of African Americans residing in Jackson, MS. CIMT was assessed by ultrasonography and represented mean far-wall thickness across right and left sides of the common carotid artery. TV viewing time, a measure of leisure sedentary behavior, and occupational sitting, a measure of non-leisure sedentary behavior, were assessed by questionnaire. RESULTS: In a multivariable regression model that included physical activity and CVD risk factors, longer TV viewing time (2-4 h/day and >4 h/day) was associated with greater CIMT (adjusted mean ± SE difference from referent [4 h/day; P-trend =0.001). In contrast, more frequent occupational sitting ('sometimes' and 'often/always') was associated with lower CIMT (adjusted mean ± SE difference from referent ['never/seldom']:-0.021 ± 0.009 mm for 'sometimes', and-0.018 ± 0.008 mm for 'often/always'; P-trend = 0.042). CONCLUSIONS: Longer TV viewing time was associated with greater CIMT, while occupational sitting was associated with lower CIMT. These findings suggest the role of sedentary behaviors in the pathogenesis of CVD among African Americans may vary by whether individuals engage in leisure versus non-leisure sedentary behaviors

    Apparent treatment-resistant hypertension and risk for stroke, coronary heart disease, and all-cause mortality

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    Apparent treatment-resistant hypertension (aTRH) is defined as uncontrolled hypertension despite the use of three or more antihypertensive medication classes or controlled hypertension while treated with four or more antihypertensive medication classes. We evaluated the association of aTRH with incident stroke, coronary heart disease (CHD), and all-cause mortality. Participants from the population-based REasons for Geographic And Racial Differences in Stroke (REGARDS) Study treated for hypertension with aTRH (n = 2043) and without aTRH (n = 12,479) were included. aTRH was further categorized as controlled aTRH (≥4 medication classes and controlled hypertension) and uncontrolled aTRH (≥3 medication classes and uncontrolled hypertension). Over a median of 5.9, 4.4, and 6.0 years of follow-up, the multivariable adjusted hazard ratio for stroke, CHD, and all-cause mortality associated with aTRH versus no aTRH was 1.25 (0.94–1.65), 1.69 (1.27–2.24), and 1.29 (1.14–1.46), respectively. Compared with controlled aTRH, uncontrolled aTRH was associated with CHD (hazard ratio, 2.33; 95% confidence interval, 1.21–4.48), but not stroke or mortality. Comparing controlled aTRH with no aTRH, risk of stroke, CHD, and all-cause mortality was not elevated. aTRH was associated with an increased risk for coronary heart disease and all-cause mortality
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