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OBJECTIVE - Patients with rheumatoid arthritis (RA) have increased cardiovascular (CV) risk. In the general population, exercise improves several CV risk factors. In a cross-sectional study, we examined the hypothesis that more exercise is associated with protective traditional and non-traditional CV risk factor profile in patients with RA.
METHODS - Patient-reported exercise outside of daily activities was quantified by time and metabolic equivalents per week (METmin/week) and CV risk factors including blood pressure, standard lipid profiles, lipoprotein particle concentrations (NMR spectroscopy), and vascular indices were measured in 165 patients with RA. The relationship between exercise and CV risk factors was assessed according to whether patients exercised or not, and after adjustment for age, race and sex.
RESULTS - Over half (54%) of RA patients did not exercise. Among those who did exercise, median value for exercise duration was 113 min/week [IQR: 60, 210], and exercise metabolic equivalent expenditure was 484 METmin/week [IQR: 258, 990]. Disease activity (measured by DAS28 score), C-reactive protein, waist-hip ratio, and prevalence of hypertension were lower in patients who exercised compared to those who did not (all p-values < 0.05) but standard lipid profile and body mass index were not significantly different. Patients who exercised had significantly higher concentrations of HDL particles (p = 0.004) and lower vascular stiffness as measured by pulse wave velocity (p = 0.005).
CONCLUSIONS - More self-reported exercise in patients with RA was associated with a protective CV risk factor profile including lower waist-hip ratio, higher HDL particle concentration, lower vascular stiffness, and a lower prevalence of hypertension.
OBJECTIVE - Currently, approximately 60-70% of patients with unilateral temporal lobe epilepsy (TLE) remain seizure-free 3 years after surgery. The goal of this work was to develop a presurgical connectivity-based biomarker to identify those patients who will have an unfavorable seizure outcome 1-year postsurgery.
METHODS - Resting-state functional and diffusion-weighted 3T magnetic resonance imaging (MRI) was acquired from 22 unilateral (15 right, 7 left) patients with TLE and 35 healthy controls. A seizure propagation network was identified including ipsilateral (to seizure focus) and contralateral hippocampus, thalamus, and insula, with bilateral midcingulate and precuneus. Between each pair of regions, functional connectivity based on correlations of low frequency functional MRI signals, and structural connectivity based on streamline density of diffusion MRI data were computed and transformed to metrics related to healthy controls of the same age.
RESULTS - A consistent connectivity pattern representing the network expected in patients with seizure-free outcome was identified using eight patients who were seizure-free at 1-year postsurgery. The hypothesis that increased similarity to the model would be associated with better seizure outcome was tested in 14 other patients (Engel class IA, seizure-free: n = 5; Engel class IB-II, favorable: n = 4; Engel class III-IV, unfavorable: n = 5) using two similarity metrics: Pearson correlation and Euclidean distance. The seizure-free connectivity model successfully separated all the patients with unfavorable outcome from the seizure-free and favorable outcome patients (p = 0.0005, two-tailed Fisher's exact test) through the combination of the two similarity metrics with 100% accuracy. No other clinical and demographic predictors were successful in this regard.
SIGNIFICANCE - This work introduces a methodologic framework to assess individual patients, and demonstrates the ability to use network connectivity as a potential clinical tool for epilepsy surgery outcome prediction after more comprehensive validation.
Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.
Emerging evidence supports an important role for T cells in the genesis of hypertension. Because this work has predominantly been performed in experimental animals, we sought to determine whether human T cells are activated in hypertension. We used a humanized mouse model in which the murine immune system is replaced by the human immune system. Angiotensin II increased systolic pressure to 162 versus 116 mm Hg for sham-treated animals. Flow cytometry of thoracic lymph nodes, thoracic aorta, and kidney revealed increased infiltration of human leukocytes (CD45(+)) and T lymphocytes (CD3(+) and CD4(+)) in response to angiotensin II infusion. Interestingly, there was also an increase in the memory T cells (CD3(+)/CD45RO(+)) in the aortas and lymph nodes. Prevention of hypertension using hydralazine and hydrochlorothiazide prevented the accumulation of T cells in these tissues. Studies of isolated human T cells and monocytes indicated that angiotensin II had no direct effect on cytokine production by T cells or the ability of dendritic cells to drive T-cell proliferation. We also observed an increase in circulating interleukin-17A producing CD4(+) T cells and both CD4(+) and CD8(+) T cells that produce interferon-γ in hypertensive compared with normotensive humans. Thus, human T cells become activated and invade critical end-organ tissues in response to hypertension in a humanized mouse model. This response likely reflects the hypertensive milieu encountered in vivo and is not a direct effect of the hormone angiotensin II.
© 2016 American Heart Association, Inc.
PURPOSE - To empirically characterize and quantify the impact of gradient weighting schemes on the appearance and fidelity of diffusion tensor imaging of the human spinal cord in vivo in clinically relevant scan time equivalents (STE).
MATERIALS AND METHODS - In five healthy controls at 3T, we evaluated test-retest reproducibility and performed voxelwise analysis of diffusion tensor imaging (DTI)-derived indices (fractional anisotropy [FA], mean [MD], axial [AD], and radial [RD] diffusivity) in the cervical spinal cord to assess spatial dependencies of measurement error and differences across three different sampling schemes (6, 15, and 32 directions) at STE of 4.5, 9, and 18 minutes. A subjective assessment was also performed.
RESULTS - With six directions, column-specific errors are highest (effect size = 2.9%, 4.4%, 7.2% for FA in dorsal column, lateral column, and gray matter) and different than the 15-direction scheme (P < 0.05). STE sequences with 15 and 32 directions exhibited small differences in error (P > 0.05). For FA and AD, measurement errors are prevalent in gray matter, while partial volume effects with cerebrospinal fluid heavily influence RD. Measurement errors decreased with increasing scan time (P < 0.01), albeit with diminishing returns at scan times longer than 9 minutes (P < 0.05).
CONCLUSION - A 15-direction scheme of 9 minutes yields measurements of the cervical spinal cord with low error. J. Magn. Reson. Imaging 2016;44:1608-1618.
© 2016 International Society for Magnetic Resonance in Medicine.
BACKGROUND - Reduced left ventricular systolic function predicts worse outcomes. However, the optimal threshold for "normal" left ventricular ejection fraction (LVEF) is uncertain. In general, LVEF ≥ 55% is considered to be "normal" by guidelines, with a low normal designation for LVEF being 50%-55%. We assessed the prognosis of participants with low normal LVEF in the Multiethnic Study of Atherosclerosis. All participants were asymptomatic and had no known clinical cardiovascular disease at baseline.
METHODS AND RESULTS - A total of 4926 out of 6814 had LVEF assessed with the use of cardiac magnetic resonance imaging (MRI), had no significant valvular disease, did not have myocardial infarction during follow-up, had complete data, and were included in this analysis. A total of 83/4926 (1.7%) had LVEF < 50% (low LVEF) and 101/4926 (2.1%) had low normal LVEF. Cox proportional hazard and cubic spline analyses were used to evaluate the association between LVEF category and 10 years of adjudicated incident congestive heart failure (CHF) and all-cause mortality adjusting for (model 1) age, sex, and race and (model 2) model 1 and diabetes mellitus, smoking, systolic blood pressure (BP), BP medications, body mass index, estimated glomerular filtration rate, low-density lipoprotein, family history of coronary heart disease, educational status, and LV mass. Mean age was 61 ± 10 years, 47% were men, 35% were on BP medications, 9% had diabetes. After 10.2 years of follow-up, 109 (2.2%) had CHF and 427 (8.7%) died. Compared with normal LVEF (≥55%), low normal LVEF and low LVEF were associated with an increased risk for incident CHF during follow-up in our multivariable Cox models: hazard ratios (HRs) 3.64 (95% CI 1.76-7.52) and 9.52 (5.63-17.52), respectively. Unlike low LVEF, low normal LVEF was not associated with increased risk of death compared with normal LVEF in our fully adjusted models: HRs 3.03 (1.94-4.73) and 1.32 (0.72-2.41), respectively. In the adjusted spline analysis HR of LVEF 55% as reference, LVEF had a U-shape association of future CHF risk and LVEF.
CONCLUSION - Low normal LVEF is as prevalent as low LVEF in asymptomatic community-dwelling adults. We observed a gradient-response association between the 3 categories of LVEF (low, low normal, and normal) and incident CHF but not for all-cause death.
Copyright © 2016 Elsevier Inc. All rights reserved.
Angiotensin-(1-7) improves glycemic control in animal models of cardiometabolic syndrome. The tissue-specific sites of action and blood pressure dependence of these metabolic effects, however, remain unclear. We hypothesized that Ang-(1-7) improves insulin sensitivity by enhancing peripheral glucose delivery. Adult male C57BL/6J mice were placed on standard chow or 60% high-fat diet for 11 weeks. Ang-(1-7) (400 ng/kg per minute) or saline was infused subcutaneously during the last 3 weeks of diet, and hyperinsulinemic-euglycemic clamps were performed at the end of treatment. High-fat fed mice exhibited modest hypertension (systolic blood pressure: 137 ± 3 high fat versus 123 ± 5 mm Hg chow;P=0.001), which was not altered by Ang-(1-7) (141 ± 4 mm Hg;P=0.574). Ang-(1-7) did not alter body weight or fasting glucose and insulin in chow or high-fat fed mice. Ang-(1-7) increased the steady-state glucose infusion rate needed to maintain euglycemia in high-fat fed mice (31 ± 5 Ang-(1-7) versus 16 ± 1 mg/kg per minute vehicle;P=0.017) reflecting increased whole-body insulin sensitivity, with no effect in chow-fed mice. The improved insulin sensitivity in high-fat fed mice was because of an enhanced rate of glucose disappearance (34 ± 5 Ang-(1-7) versus 20 ± 2 mg/kg per minute vehicle;P=0.049). Ang-(1-7) enhanced glucose uptake specifically into skeletal muscle by increasing translocation of glucose transporter 4 to the sarcolemma. Our data suggest that Ang-(1-7) has direct insulin-sensitizing effects on skeletal muscle, independent of changes in blood pressure. These findings provide new insight into mechanisms by which Ang-(1-7) improves insulin action, and provide further support for targeting this peptide in cardiometabolic disease.
© 2016 American Heart Association, Inc.
We recently reported our findings of resting state functional connectivity in the human spinal cord: in a cohort of healthy volunteers we observed robust functional connectivity between left and right ventral (motor) horns and between left and right dorsal (sensory) horns (Barry et al., 2014). Building upon these results, we now quantify the within-subject reproducibility of bilateral motor and sensory networks (intraclass correlation coefficient=0.54-0.56) and explore the impact of including frequencies up to 0.13Hz. Our results suggest that frequencies above 0.08Hz may enhance the detectability of these resting state networks, which would be beneficial for practical studies of spinal cord functional connectivity.
Copyright © 2016 Elsevier Inc. All rights reserved.
UNLABELLED - Quantification of β-amyloid (Aβ) in vivo is often accomplished using the distribution volume ratio (DVR), based on a simplified reference tissue model. We investigated the local relationships between DVR and cerebral blood flow (CBF), as well as relative CBF (R1), in nondemented older adults.
METHODS - Fifty-five nondemented participants (mean age, 78.5 y) in the Baltimore Longitudinal Study of Aging underwent (15)O-H2O PET CBF and dynamic (11)C-PiB PET. (15)O-H2O PET images were normalized and smoothed using SPM. A simplified reference tissue model with linear regression and spatial constraints was used to generate parametric DVR images. The DVR images were regressed on CBF images on a voxel-by-voxel basis using robust biologic parametric mapping, adjusting for age and sex (false discovery rate, P = 0.05; spatial extent, 50 voxels). DVR images were also regressed on R1 images, a measure of the transport rate constant from vascular space to tissue. All analyses were performed on the entire sample, and on high and low tertiles of mean cortical DVR.
RESULTS - Voxel-based analyses showed that increased DVR is associated with increased CBF in the frontal, parietal, temporal, and occipital cortices. However, this association appears to spare regions that typically show early Aβ deposition. A more robust relationship between DVR and CBF was observed in the lower tertile of DVR, that is, negligible cortical Aβ load, compared with the upper tertile of cortical DVR and Aβ load. The spatial distributions of the DVR-CBF and DVR-R1 correlations showed similar patterns. No reliable negative voxelwise relationships between DVR and CBF or R1 were observed.
CONCLUSION - Robust associations between DVR and CBF at negligible Aβ levels, together with similar spatial distributions of DVR-CBF and DVR-R1 correlations, suggest that regional distribution of DVR reflects blood flow and tracer influx rather than pattern of Aβ deposition in those with minimal Aβ load. DVR-CBF associations in individuals with a higher DVR are more likely to reflect true associations between patterns of Aβ deposition and CBF or neural activity. These findings have important implications for analysis and interpretation of voxelwise correlations with external variables in individuals with varying amounts of Aβ load.
© 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
UNLABELLED - Nonalcoholic fatty liver disease (NAFLD) and heart failure (HF) are obesity-related conditions with high cardiovascular mortality. Whether NAFLD is independently associated with subclinical myocardial remodeling or dysfunction among the general population is unknown. We performed a cross-sectional analysis of 2,713 participants from the multicenter, community-based Coronary Artery Risk Development in Young Adults (CARDIA) study who underwent concurrent computed tomography (CT) quantification of liver fat and comprehensive echocardiography with myocardial strain measured by speckle tracking during the Year-25 examination (age, 43-55 years; 58.8% female and 48.0% black). NAFLD was defined as liver attenuation ≤40 Hounsfield units after excluding other causes of liver fat. Subclinical left ventricular (LV) systolic dysfunction was defined using values of absolute peak global longitudinal strain (GLS). Diastolic dysfunction was defined using Doppler and tissue Doppler imaging markers. Prevalence of NAFLD was 10.0%. Participants with NAFLD had lower early diastolic relaxation (e') velocity (10.8 ± 2.6 vs. 11.9 ± 2.8 cm/s), higher LV filling pressure (E/e' ratio: 7.7 ± 2.6 vs. 7.0 ± 2.3), and worse absolute GLS (14.2 ± 2.4% vs. 15.2 ± 2.4%) than non-NAFLD (P < 0.0001 for all). When adjusted for HF risk factors or body mass index, NAFLD remained associated with subclinical myocardial remodeling and dysfunction (P < 0.01). The association of NAFLD with e' velocity (β = -0.36 [standard error = 0.15] cm/s; P = 0.02), E/e' ratio (β = 0.35 [0.16]; P = 0.03), and GLS (β = -0.42 [0.18]%; P = 0.02) was attenuated after controlling for visceral adipose tissue. Effect modification by race and sex was not observed.
CONCLUSIONS - NAFLD is independently associated with subclinical myocardial remodeling and dysfunction and provides further insight into a possible link between NAFLD and HF.
© 2015 by the American Association for the Study of Liver Diseases.