1. |
- Sundström, Johan, et al.
(author)
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Relations of plasma matrix metalloproteinase-9 to clinical cardiovascular risk factors and echocardiographic left ventricular measures : the Framingham Heart Study.
- 2004
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In: Circulation. - 1524-4539. ; 109:23, s. 2850-6
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Journal article (peer-reviewed)abstract
- BACKGROUND: Plasma levels of matrix metalloproteinase-9 (MMP-9), a key determinant of extracellular matrix degradation, are increased in heart failure and in acute coronary syndromes. We investigated cross-sectional relations of plasma MMP-9 to vascular risk factors and echocardiographic left ventricular (LV) measurements. METHODS AND RESULTS: We studied 699 Framingham Study participants (mean age, 57 years; 58% women), free of heart failure and previous myocardial infarction, who underwent routine echocardiography. We examined sex-specific distributions of LV internal dimensions (LVEDD) and wall thickness (LVWT) and sampled persons with both LVEDD and LVWT below the sex-specific median (referent, n=299), with increased LVEDD (LVEDD > or =90th percentile, n=204) and increased LVWT (LVWT > or =90th percentile, n=221) in a 3:2:2 ratio. Plasma MMP-9 was detectable in 138 persons (20%). In multivariable models, increasing heart rate (OR per SD, 1.41; 95% CI, 1.17 to 1.71) and antihypertensive treatment (OR, 1.63; 95% CI, 1.06 to 2.50) were key clinical correlates of detectable plasma MMP-9. In multivariable-adjusted models, detectable plasma MMP-9 was associated with increased LVEDD (OR, 2.84; 95% CI, 1.13 to 7.11), increased LVWT (OR, 2.54; 95% CI, 1.00 to 6.46), and higher LV mass (P=0.06) in men but not in women (OR for increased LVEDD, 1.37; 95% CI, 0.54 to 3.46; for increased LVWT, 0.99; 95% CI, 0.39 to 2.52; P=0.59 for LV mass). CONCLUSIONS: In our community-based sample, detectable plasma MMP-9 levels were associated with increased LV diastolic dimensions and increased wall thickness in men. These observations indicate that plasma MMP-9 level may be a marker for cardiac extracellular matrix degradation, a process involved in LV remodeling.
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2. |
- Sundström, Johan, et al.
(author)
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Relations of plasma total TIMP-1 levels to cardiovascular risk factors and echocardiographic measures : the Framingham heart study.
- 2004
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In: Eur Heart J. - 0195-668X. ; 25:17, s. 1509-16
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Journal article (peer-reviewed)abstract
- AIMS: Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a key regulator of extracellular matrix degradation. We examined relations of plasma total TIMP-1 to cardiovascular risk factors and echocardiographic left ventricular (LV) structure and function in a community-based sample. METHODS AND RESULTS: We studied 1069 Framingham Heart Study participants (mean age 56 years, 58% women) free of heart failure and previous myocardial infarction. Plasma TIMP-1 was higher in men compared with women, and increased with age, body mass index and total/HDL-cholesterol ratio, but decreased with alcohol intake. Plasma TIMP-1 was also directly related to smoking, diabetes and use of anti-hypertensive treatment. Adjusting for age, sex and height, plasma TIMP-1 was positively associated with LV mass, wall thickness, relative wall thickness, end-systolic diameter, and left atrial diameter and the risk of having increased LV end-diastolic diameter or increased wall thickness, and negatively correlated with fractional shortening. Additional adjustment for clinical covariates attenuated the relations of plasma TIMP-1 to most echocardiographic measures. CONCLUSIONS: In our cross-sectional investigation, plasma total TIMP-1 was related to major cardiovascular risk factors and to indices of LV hypertrophy and systolic dysfunction. This raises the possibility that cardiovascular risk factors may influence cardiovascular remodelling via extracellular matrix degradation, which may be reflected in plasma TIMP-1 levels.
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3. |
- Vasan, Ramachandran S, et al.
(author)
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Relations of serum aldosterone to cardiac structure : gender-related differences in the Framingham Heart Study.
- 2004
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In: Hypertension. - 1524-4563. ; 43:5, s. 957-62
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Journal article (peer-reviewed)abstract
- Aldosterone is associated with myocardial fibrosis in experimental studies and with left ventricular remodeling in heart failure patients. We hypothesized that aldosterone influences ventricular remodeling in people without congestive heart failure in the community. We examined the relations between serum aldosterone and echocardiographic left ventricular measurements in 2820 Framingham Study subjects (mean age 57 years, 58% women, 88% white) free of myocardial infarction and overt heart failure. Serum aldosterone levels were higher in women compared with men. In linear regression models (adjusted for age, systolic blood pressure, weight, height, diabetes, heart rate, hypertension treatment, and ethnicity), left ventricular wall thickness and relative wall thickness were positively related, and left ventricular diastolic dimensions were inversely related to serum aldosterone in women (P<0.05 for all), but not in men (P>0.20 for all). There was no effect modification of the relations observed in women by menopausal status. The gender-related differences in relations of serum aldosterone to relative wall thickness were consistent across subgroups defined on the basis of sex-specific median values of systolic blood pressure and body mass index. Fractional shortening, left ventricular mass, and left atrial dimensions were not related to serum aldosterone in either sex. In conclusion, in our community-based sample of individuals free of myocardial infarction and heart failure, serum aldosterone was positively associated with a left ventricular geometric pattern suggestive of concentric remodeling (increased left ventricular wall thickness and relative wall thickness but decreased internal dimensions) in women but not in men. Additional investigations are warranted to confirm these findings.
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4. |
- Landström, Daniel, et al.
(author)
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Symbol time offset estimation in coherent OFDM systems
- 2002
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In: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778. ; 50:4, s. 545-549
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Journal article (peer-reviewed)abstract
- This paper presents a symbol time offset estimator for coherent orthogonal frequency division multiplexing (OFDM) systems. The estimator exploits both the redundancy in the cyclic prefix and available pilot symbols used for channel estimation. The estimator is robust against frequency offsets and is suitable for use in dispersive channels. We base the estimator on the maximum-likelihood estimator for the additive white Gaussian noise channel. Simulations for an example system indicate a system performance as close as 0.6 dB to a perfectly synchronized system.
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5. |
- Sundström, Johan, et al.
(author)
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Plasma homocysteine, hypertension incidence, and blood pressure tracking : the Framingham Heart Study.
- 2003
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In: Hypertension. - 1524-4563. ; 42:6, s. 1100-5
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Journal article (peer-reviewed)abstract
- Plasma homocysteine is cross-sectionally associated with blood pressure in large, community-based studies. It is unknown whether elevated plasma homocysteine predicts hypertension incidence. We investigated the relations of baseline plasma total homocysteine levels to hypertension incidence and blood pressure tracking in 2104 Framingham Heart Study participants (mean age, 57 years; 58% women), who were free of hypertension, myocardial infarction, heart failure, atrial fibrillation, or renal failure at baseline. Baseline mean+/-SD plasma homocysteine was 10.1+/-3.7 micromol/L. On follow-up 4 years from baseline, 360 persons (17.1%) had developed hypertension, and 878 persons (41.7%) had progressed to a higher blood pressure stage. In unadjusted analyses, a 1-SD higher log homocysteine value was associated with increased odds of developing hypertension (odds ratio [OR], 1.18; 95% confidence interval [CI], 1.05 to 1.32) and increased odds of blood pressure progression (OR, 1.17; 95% CI, 1.07 to 1.27). The relations of plasma homocysteine to the incidence of hypertension or blood pressure progression were statistically nonsignificant in age- and sex-adjusted logistic regression models (OR, 0.98; 95% CI, 0.87 to 1.11 and OR, 1.05; 95% CI, 0.96 to 1.16, respectively) and in multivariable models adjusted for age, sex, body mass index, diabetes, interim weight change, smoking, serum creatinine, baseline blood pressure, and blood pressure category (OR, 0.92; 95% CI, 0.81 to 1.06 and OR, 1.07; 95% CI, 0.97 to 1.18, respectively). In conclusion, we found no major relation of baseline plasma homocysteine levels to hypertension incidence or longitudinal blood pressure progression in a large, community-based cohort of nonhypertensive individuals after adjustment for age, sex, and other important covariates.
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6. |
- Sundström, Johan, et al.
(author)
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Relations of plasma homocysteine to left ventricular structure and function : the Framingham Heart Study.
- 2004
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In: Eur Heart J. - 0195-668X. ; 25:6, s. 523-30
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Journal article (peer-reviewed)abstract
- AIMS: Hyperhomocysteinaemia is a risk factor for congestive heart failure, especially in women. We investigated if homocysteine promotes left ventricular (LV) remodelling. METHODS AND RESULTS: We examined cross-sectional relations of plasma total homocysteine to echocardiographic LV structure and function in 2697 Framingham Heart Study participants (mean age 58 years, 58% women) free of heart failure and previous myocardial infarction. Adjusting for age and height, plasma homocysteine was positively related to LV mass, wall thickness, and relative wall thickness in women (p=0.0004-0.04), but not in men (p=0.28-0.68). Adjusting additionally for other clinical covariates, the relations of plasma homocysteine to LV mass and wall thickness in women remained statistically significant, but the relation to relative wall thickness became of borderline significance (1.92 g, 0.01 cm, and 0.29% increase, respectively, for a 1-SD increase in ln[homocysteine], p=0.01-0.08). LV mass and wall thickness were higher in the fourth quartile of plasma homocysteine compared to the lower three in all models in women (p=0.0003-0.02), but not in men (p=0.25-0.78). Plasma homocysteine was not related to left atrial size or LV fractional shortening in either sex. CONCLUSION: In our community-based sample, plasma homocysteine was directly related to LV mass and wall thickness in women but not in men.
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7. |
- van de Beek, Jan-Jaap, et al.
(author)
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Three non-pilot based time- and frequency estimators for OFDM
- 2000
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In: Signal Processing. - 0165-1684 .- 1872-7557. ; 80:7, s. 1321-1334
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Journal article (peer-reviewed)abstract
- Time-domain maximum-likelihood (ML) estimators of time and frequency offsets are derived for three orthogonal frequency division multiplexing (OFDM) signal models: a pulse-shaped one-shot OFDM signal, a stream of multiple OFDM signals and an OFDM signal in a dispersive channel environment. We then develop structures to simplify their implementation. Simulation results show the relative performance and strengths of each of these three estimators.
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