University of Luxembourg

About: University of Luxembourg is a education organization based out in Luxembourg, Luxembourg. It is known for research contribution in the topics: Population & European union. The organization has 4744 authors who have published 22175 publications receiving 381824 citations.

Resting Pd/Pa measured with intracoronary pressure wire strongly predicts fractional flow reserve.

Abstract: OBJECTIVE: To investigate the relationship between resting distal coronary pressure to aortic pressure ratio (Pd/Pa) and fractional flow reserve (FFR) obtained during maximal hyperemia. BACKGROUND: FFR is an invasive index of the functional severity of a coronary artery stenosis determined from coronary pressure measurements. It is generally believed that there is little correlation between resting Pd/Pa and FFR obtained during maximal hyperemia. We have therefore studied this relationship in a large cohort of patients who had undergone pressure- wire assessments. METHODS: 528 consecutive pressure-wire studies performed in 483 patients over a 2-year period were retrospectively analyzed. RESULTS: A linear correlation between resting Pd/Pa and FFR post-pharmacological hyperemia was observed (rho = 0.74; p or = 0.93 (> or = 0.96) had a negative predictive value (NPV) of 95.7% (93%). CONCLUSIONS: We demonstrate a strong correlation between resting Pd/Pa and FFR. Resting values of Pd/Pa can be used to predict a positive FFR result with relatively high PPV and NPV. This may potentially obviate the need for adenosine infusion in a proportion of pressure-wire studies.

Cryptanalysis of EC-RAC, a RFID Identification Protocol

Abstract: At RFID'08, Lee et al. have proposed a RFID scheme based on elliptic curve cryptography. This scheme, called Elliptic Curve Random Access Control (EC-RAC) has been conceived in order to be implemented on an efficient security processor designed for RFID tags. The aim of this scheme is to enable a fast, secure and private identification scheme. Security arguments are given to prove that RFID tags implementing this scheme are neither traceable nor cloneable. We here show how tags can be tracked if one has eavesdropped the same tag twice and we show that a tag can be impersonated if it has been passively eavesdropped three times. We propose a new scheme based on a modification of the Schnorr scheme as efficient as the initial scheme. We prove that this scheme is zero-knowledge, sound against active adversaries. Moreover, our proposal is private under the Decisional Diffie-Hellman assumption.

Personalized whole-body models integrate metabolism, physiology, and the gut microbiome.

Abstract: Comprehensive molecular-level models of human metabolism have been generated on a cellular level. However, models of whole-body metabolism have not been established as they require new methodological approaches to integrate molecular and physiological data. We developed a new metabolic network reconstruction approach that used organ-specific information from literature and omics data to generate two sex-specific whole-body metabolic (WBM) reconstructions. These reconstructions capture the metabolism of 26 organs and six blood cell types. Each WBM reconstruction represents whole-body organ-resolved metabolism with over 80,000 biochemical reactions in an anatomically and physiologically consistent manner. We parameterized the WBM reconstructions with physiological, dietary, and metabolomic data. The resulting WBM models could recapitulate known inter-organ metabolic cycles and energy use. We also illustrate that the WBM models can predict known biomarkers of inherited metabolic diseases in different biofluids. Predictions of basal metabolic rates, by WBM models personalized with physiological data, outperformed current phenomenological models. Finally, integrating microbiome data allowed the exploration of host-microbiome co-metabolism. Overall, the WBM reconstructions, and their derived computational models, represent an important step toward virtual physiological humans.

Conditional Neuronal Nitric Oxide Synthase Overexpression Impairs Myocardial Contractility

Abstract: The role of the neuronal NO synthase (nNOS or NOS1) enzyme in the control of cardiac function still remains unclear. Results from nNOS / mice or from pharmacological inhibition of nNOS are contradictory and do not pay tribute to the fact that probably spatial confinement of the nNOS enzyme is of major importance. We hypothesize that the close proximity of nNOS and certain effector molecules like L-type Ca 2 -channels has an impact on myocardial contractility. To test this, we generated a new transgenic mouse model allowing conditional, myocardial specific nNOS overexpression. Western blot analysis of transgenic nNOS overexpression showed a 6-fold increase in nNOS protein expression compared with noninduced littermates (n12; P0.01). Measuring of total NOS activity by conversion of ( 3 H)-L-arginine to ( 3 H)-L-citrulline showed a 30% increase in nNOS overexpressing mice (n18; P0.05). After a 2 week induction, nNOS overexpression mice showed reduced myocardial contractility. In vivo examinations of the nNOS overexpressing mice revealed a 173% decrease of dp/dtmax compared with noninduced mice (P0.05). Likewise, ejection fraction was reduced significantly (42% versus 65%; n15; P0.05). Interestingly, coimmunoprecipitation experiments indicated interaction of nNOS with SR Ca 2 ATPase and additionally with L-type Ca 2 - channels in nNOS overexpressing animals. Accordingly, in adult isolated cardiac myocytes, ICa,L density was significantly decreased in the nNOS overexpressing cells. Intracellular Ca 2 -transients and fractional shortening in cardiomyocytes were also clearly impaired in nNOS overexpressing mice versus noninduced littermates. In conclusion, conditional myocardial specific overexpression of nNOS in a transgenic animal model reduced myocardial contractility. We suggest that nNOS might suppress the function of L-type Ca 2 -channels and in turn reduces Ca 2 -transients which accounts for the negative inotropic effect. (Circ Res. 2007;100:e32-e44.)