Background-Carotid atherosclerosis, measured as carotid intima-media thickness or as characteristics of plaques, has been linked to cardiovascular disease (CVD) and to C-reactive protein (CRP) levels. We investigated the relationship between carotid atherosclerosis and CRP and their joint roles in CVD prediction. Methods and Results-Of 5888 participants in the Cardiovascular Health Study, an observational study of adults aged Ն65 years, 5020 without baseline CVD were included in the analysis. They were followed up for as long as 12 years for CVD incidence and all-cause mortality after baseline ultrasound and CRP measurement. When CRP was elevated (Ͼ3 mg/L) among those with detectable atherosclerosis on ultrasound, there was a 72% (95% CI, 1.46 to 2.01) increased risk for CVD death and a 52% (95% CI, 1.37 to 1.68) increased risk for all-cause mortality. Elevated CRP in the absence of atherosclerosis did not increase CVD or all-cause mortality risk. The proportion of excess risk attributable to the interaction of high CRP and atherosclerosis was 54% for CVD death and 79% for all-cause mortality. Addition of CRP or carotid atherosclerosis to conventional risk factors modestly increased in the ability to predict CVD, as measured by the c statistic. Conclusions-In older adults, elevated CRP was associated with increased risk for CVD and all-cause mortality only in those with detectable atherosclerosis based on carotid ultrasound. Despite the significant associations of CRP and carotid atherosclerosis with CVD, these measures modestly improve the prediction of CVD outcomes after one accounts for the conventional risk factors. (Circulation. 2007;116:32-38.)

HE PREVALENCE AND PROGNOsis of unrecognized myocardial infarction (MI) in older people with and without diabetes may be higher than previously suspected in population studies. [1][2][3][4] Advances in MI detection, such as cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE), are more sensitive than prior methods. 5 Ascertaining the prevalence of unrecognized MI (UMI) in these groups is relevant because age and diabetes increase the risks of coronary heart disease. 6 Pathologic studies 7 indicate that subclinical coronary plaque rupture occurs frequently, particularly in diabetic individuals, which may culminate in a high prevalence of UMI.Several population studies 1-4 have described the prevalence of UMI based on electrocardiography (ECG), but ECG Author Affiliations are listed at the end of this article.

The idea that enzymes catalyze reactions by dynamical coupling between the conformational motions and the chemical coordinates has recently attracted major experimental and theoretical interest. However, experimental studies have not directly established that the conformational motions transfer energy to the chemical coordinate, and simulating enzyme catalysis on the relevant timescales has been impractical. Here, we introduce a renormalization approach that transforms the energetics and dynamics of the enzyme to an equivalent low-dimensional system, and allows us to simulate the dynamical coupling on a ms timescale. The simulations establish, by means of several independent approaches, that the conformational dynamics is not remembered during the chemical step and does not contribute significantly to catalysis. Nevertheless, the precise nature of this coupling is a question of great importance.adenylate kinase ͉ coarse-grained model ͉ renormalization ͉ simplified model ͉ enzyme catalysis

The proposal that enzymatic catalysis is due to conformational fluctuations has been previously promoted by means of indirect considerations. However, recent works have focused on cases where the relevant motions have components toward distinct conformational regions, whose population could be manipulated by mutations. In particular, a recent work has claimed to provide direct experimental evidence for a dynamical contribution to catalysis in dihydrofolate reductase, where blocking a relevant conformational coordinate was related to the suppression of the motion toward the occluded conformation. The present work utilizes computer simulations to elucidate the true molecular basis for the experimentally observed effect. We start by reproducing the trend in the measured change in catalysis upon mutations (which was assumed to arise as a result of a "dynamical knockout" caused by the mutations). This analysis is performed by calculating the change in the corresponding activation barriers without the need to invoke dynamical effects. We then generate the catalytic landscape of the enzyme and demonstrate that motions in the conformational space do not help drive catalysis. We also discuss the role of flexibility and conformational dynamics in catalysis, once again demonstrating that their role is negligible and that the largest contribution to catalysis arises from electrostatic preorganization. Finally, we point out that the changes in the reaction potential surface modify the reorganization free energy (which includes entropic effects), and such changes in the surface also alter the corresponding motion. However, this motion is never the reason for catalysis, but rather simply a reflection of the shape of the reaction potential surface.T he enormous catalytic power of enzymes has been attempted to be rationalized by several proposals. Here, we would like to focus on a specific proposal that appears to be gaining significant support. Namely, there exists a long-standing assumption that enzyme dynamics and flexibility are important to the chemical step of catalysis (see, e.g., refs. 1-4 and references cited therein). This hypothesis has emerged in several forms, ranging from the assumption that enzymatic catalysis can be linked to lid closures upon binding (e.g., ref. 5) to more recent studies (6, 7) that considered the effect of modifying the accessibility of conformational states separated by relatively small structural differences. It was then argued that the observed changes in the rate of the chemical step upon mutations that appear to prevent the flexibility of the active-site residues could be interpreted as evidence for a dynamical coupling to catalysis. This proposal is particularly well defined in a recent study (6) that focused on dihydrofolate reductase (DHFR). That is, ref. 6 demonstrated that the N23PP, S148A, and N23PP/S148A mutants of DHFR have more limited conformational flexibility than the WT and cannot access the occluded (OC) conformation from the closed (CL) conformation, which is available to th...

One of the fundamental challenges in biotechnology and in biochemistry is the ability to design effective enzymes. Doing so would be a convincing manifestation of a full understanding of the origin of enzyme catalysis. Despite an impressive progress, most of the advances on this front have been made by placing the reacting fragments in the proper places, rather than by optimizing the environment preorganization, which is the key factor in enzyme catalysis. Rational improvement of the preorganization would require approaches capable of evaluating reliably the actual catalytic effect. This work takes apreviously designed kemp eliminases as a benchmark for a computer aided enzyme design, using the empirical valence bond as the main screening tool. The observed absolute catalytic effect and the effect of directed evolution are reproduced and analyzed (assuming that the substrate is in the designed site). It is found that, in the case of kemp eliminases, the transition state charge distribution makes it hard to exploit the active site polarity, even with the ability to quantify the effect of different mutations. Unexpectedly, it is found that the directed evolution mutants lead to the reduction of solvation of the reactant state by water molecules rather that to the more common mode of transition state stabilization used by naturally evolved enzymes. Finally it is pointed out that our difficulties in improving Kemp eliminase are not due to overlooking exotic effect, but to the challenge in designing a preorganized environment that would exploit the small change it charge distribution during the formation of the transition state.computer aided enzyme design | empirical valence bond | directed evolution R ational enzyme design is expected to have a great potential in industrial application and eventually in medicine (1). Furthermore, the ability to design efficient enzymes might be considered as the best manifestation of a true understanding of enzyme catalysis. However, at present there has been a limited success in most attempts of rational enzyme design, and the resulting constructs have been much less effective than the corresponding natural enzymes (1). Furthermore, despite the progress in directed evolution (e.g., ref.2), we do not have unique rationales for the resulting rate enhancements.Most attempts to identify the problems with the current rational design approaches (for review, see ref. 1) have not been based on actual simulations of the given effect. In fact, it has been argued (3,4), that the problems are due to the incomplete modeling of the transition state (TS) and to the limited awareness to the key role of the reorganization energy. Even a recent attempt to use a molecular orbital-combined quantum mechanical /molecular mechanics (MO-QM/MM) approach (5) has not provided a reasonable estimate of the observed catalytic effect or the trend of the mutational effects in an artificially design enzyme. Thus, reproducing the effect of directed evolution and eventually obtaining better performance in enzyme de...

EAT volume was higher and density lower in subjects with coronary calcium compared to subjects with CCS = 0, with similar EAT volume in CCS<100 and CCS≥100. Lower EAT density and increased EAT volume were associated with coronary calcification, serum levels of plaque inflammatory markers and MACE, suggesting that dysfunctional EAT may be linked to early plaque formation and inflammation.

Background-Increased carotid artery intima-media thickness (IMT) and elevated C-reactive protein (CRP) are both associated with the occurrence of stroke. We investigated whether elevated CRP is a risk factor for ischemic stroke independent of carotid IMT and studied the interaction between CRP and IMT. Methods and Results-We studied 5417 participants aged 65 years or older without preexisting stroke or chronic atrial fibrillation who were participants in the Cardiovascular Health Study. The hazard ratio of incident ischemic stroke was estimated by Cox proportional hazards regression. During 10.2 years of follow-up, 469 incident ischemic strokes occurred. The adjusted hazard ratios for ischemic stroke in the 2nd to 4th quartiles of baseline CRP, relative to the 1st quartile, were 1.19 (95% CI 0.92 to 1.53), 1.05 (95% CI 0.81 to 1.37), and 1.60 (95% CI 1.23 to 2.08), respectively. With additional adjustment for carotid IMT, there was little confounding. The association of CRP with stroke was significantly different depending on IMT (PϽ0.02), with no association of CRP with stroke among those in the lowest IMT tertile and a significant association among those with higher levels of IMT. Conclusions-We conclude that elevated CRP is a risk factor for ischemic stroke, independent of atherosclerosis severity as measured by carotid IMT. The association of CRP with stroke is more apparent in the presence of a higher carotid IMT. CRP and carotid IMT may each be independent integrals in determining the risk of ischemic stroke.

One of the fundamental challenges in biotechnology and biochemistry is the ability to design effective enzymes. Despite recent progress, most of the advances on this front have been made by placing the reacting fragments in the proper places, rather than by optimizing the preorganization of the environment, which is the key factor in enzyme catalysis. Thus, rational improvement of the preorganization would require approaches capable of evaluating reliably the actual catalytic effect. This work considers the catalytic effects in different Kemp eliminases as a benchmark for a computer aided enzyme design. It is shown that the empirical valence bond provides a powerful screening tool, with significant advantage over current alternative strategies. The insights provided by the empirical valence bond calculations are discussed emphasizing the ability to analyze the difference between the linear free energy relationships obtained in solution to those found in the enzymes. We also point out the trade off between reliability and speed of the calculations and try to determine what it takes to obtain reliable computer aided screening.