Gold plated rings: N‐Propargylcarboxamides (1) when reacted with a gold complex containing the IPr N‐heterocyclic carbene ligand, delivers the first isolable vinylgold intermediates obtained from ...alkynes. see Scheme; IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylide
Organic Rankine Cycles (ORCs) are particularly suitable for recovering energy from low-grade heat sources. This paper describes the behavior of a small-scale ORC used to recover energy from a ...variable flow rate and temperature waste heat source. A traditional static model is unable to predict transient behavior in a cycle with a varying thermal source, whereas this capability is essential for simulating an appropriate cycle control strategy during part-load operation and start and stop procedures. A dynamic model of the ORC is therefore proposed focusing specifically on the time-varying performance of the heat exchangers, the dynamics of the other components being of minor importance. Three different control strategies are proposed and compared. The simulation results show that a model predictive control strategy based on the steady-state optimization of the cycle under various conditions is the one showing the best results.
Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a recently described method of post processing routine cine acquisitions which aims to provide quantitative measurements of ...circumferentially and radially directed ventricular wall strain. Inter-study reproducibility is important for serial assessments however has not been defined for CMR-FT.
16 healthy volunteers were imaged 3 times within a single day. The first examination was performed at 0900 after fasting and was immediately followed by the second. The third, non-fasting scan, was performed at 1400.CMR-FT measures of segmental and global strain parameters were calculated. Left ventricular (LV) circumferential and radial strain were determined in the short axis orientation (Ecc(SAX) and Err(SAX) respectively). LV and right ventricular longitudinal strain and LV radial strain were determined from the 4-chamber orientation (Ell(LV), Ell(RV), and Err(LAX) respectively). LV volumes and function were also analysed.Inter-study reproducibility and study sample sizes required to demonstrate 5% changes in absolute strain were determined by comparison of the first and second exams. The third exam was used to determine whether diurnal variation affected reproducibility.
CMR-FT strain analysis inter-study reproducibility was variable. Global strain assessment was more reproducible than segmental analysis. Overall Ecc(SAX) was the most reproducible measure of strain: coefficient of variation (CV) 38% and 20.3% and intraclass correlation coefficient (ICC) 0.68 (0.55-0.78) and 0.7 (0.32-0.89) for segmental and global analysis respectively. The least reproducible segmental measure was Ell(RV): CV 60% and ICC 0.56 (0.41-0.69) whilst the least reproducible global measure was Err(LAX): CV 33.3% and ICC 0.44 (0-0.77). Variable reproducibility was also reflected in the calculated sample sizes, which ranged from 11 (global Ecc(SAX)) to 156 subjects (segmental Ell(RV)). The reproducibility of LV volumes and function was excellent. There was no diurnal variation in global strain or LV volumetric measurements.
Inter-study reproducibility of CMR-FT varied between different parameters, as summarized above and was better for global rather than segmental analysis. It was not measurably affected by diurnal variation. CMR-FT may have potential for quantitative wall motion analysis with applications in patient management and clinical trials. However, inter-study reproducibility was relatively poor for segmental and long axis analyses of strain, which have yet to be validated, and may benefit from further development.
Heart failure with preserved ejection fraction is an increasing challenge for modern day medicine and has been drawing more attention recently. Invasive right heart catheterization represents the ...mainstay for the diagnosis of diastolic dysfunction, however due to its attributable risk of an invasive procedure, other non-invasive clinical pathways are trying to approach this pathology in clinical practice. Diastolic failure is complex, and imaging is based on various parameters. In addition to transthoracic echocardiography, numerous novel imaging approaches, such as cardiac magnetic resonance imaging, computed tomography, positron emission (computed) tomography or single photon emission computed tomography techniques are being used to supplement deeper insights into causal pathology and might open targets for dedicated therapy options. This article provides insights into these sophisticated imaging techniques, their incremental value for the diagnosis of this poorly understood disease and recent promising results for an enhanced prognostication of outcome and therapy monitoring.
The aims of the study were to assess the prognostic significance of cardiac magnetic resonance myocardial feature tracking (CMR-FT) in a large multicenter study and to evaluate the most potent CMR-FT ...predictor of hard clinical events following myocardial infarction (MI).
CMR-FT is a new method that allows accurate assessment of global and regional circumferential, radial, and longitudinal myocardial strain. The prognostic value of CMR-FT in patients with reperfused MI is unknown.
The study included 1,235 MI patients (n = 795 with ST-segment elevation MI and 440 with non–ST-elevation MI) at 15 centers. All patients were reperfused by primary percutaneous coronary intervention. Central core laboratory–masked analyses were performed to determine left ventricular (LV) circumferential, radial, and longitudinal strain. The primary clinical endpoint of the study was the occurrence of major adverse cardiac events within 12 months after infarction.
Patients with cardiovascular events had significantly impaired CMR-FT strain values (p < 0.001 for all). Global longitudinal strain was identified as the strongest CMR-FT parameter of future cardiovascular events and emerged as an independent predictor of poor prognosis following MI even after adjustment for established prognostic markers. Global longitudinal strain provided an incremental prognostic value for all-cause mortality above LV ejection fraction (c-index increase from 0.65 to 0.73; p = 0.04) and infarct size (c-index increase from 0.60 to 0.78; p = 0.002).
CMR-FT is a superior measure of LV function and performance early after reperfused MI with incremental prognostic value for mortality over and above LV ejection fraction and infarct size. (Abciximab i.v. Versus i.c. in ST-segment elevation Myocardial Infarction AIDA STEMI; NCT00712101; Thrombus Aspiration in ThrOmbus Containing culpRIT Lesions in Non-ST-Elevation Myocardial Infarction TATORT-NSTEMI; NCT01612312)
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A new, highly efficient, and atom-economic access to a series of functionalized 2,5-disubstituted oxazoles from propargylic amides is reported. A series of propargylic amides were transformed to the ...corresponding alkylideneoxazolines by a gold(I) catalyst. The next step was an autoxidation to hydroperoxides bearing the heteroaromatic oxazoles. Experiments addressing the reaction mechanism reveal a radical pathway for this autoxidation process. The hydroperoxides could conveniently be converted to the corresponding alcohols by reduction with sodium borohydride.
When an ynamide meets a gold carbenoid: Highly electrophilic gold carbenoids available from propargylic esters by means of 1,2‐acyloxy migration open up new reaction pathways for ynamide gold ...chemistry. In this way highly functionalized cyclopentadiene derivatives become accessible (see scheme; EWG=electron‐withdrawing group).
Objectives This study sought to compare the diagnostic performance of a multidetector computed tomography (MDCT) integrated protocol (IP) including coronary angiography (CTA) and stress-rest ...perfusion (CTP) with cardiac magnetic resonance myocardial perfusion imaging (CMR-Perf) for detection of functionally significant coronary artery disease (CAD). Background MDCT stress-rest perfusion methods were recently described as adjunctive tools to improve CTA accuracy for detection of functionally significant CAD. However, only a few studies compared these MDCT-IP with other clinically validated perfusion techniques like CMR-Perf. Furthermore, CTP has never been validated against the invasive reference standard, fractional flow reserve (FFR), in patients with suspected CAD. Methods 101 symptomatic patients with suspected CAD (62 ± 8.0 years, 67% males) and intermediate/high pre-test probability underwent MDCT, CMR and invasive coronary angiography. Functionally significant CAD was defined by the presence of occlusive/subocclusive stenoses or FFR measurements ≤0.80 in vessels >2mm. Results On a patient-based model, the MDCT-IP had a sensitivity, specificity, positive and negative predictive values of 89%, 83%, 80% and 90%, respectively (global accuracy 85%). These results were closely related with those achieved by CMR-Perf: 89%, 88%, 85% and 91%, respectively (global accuracy 88%). When comparing test accuracies using noninferiority analysis, differences greater than 11% in favour of CMR-Perf can be confidently excluded. Conclusions MDCT protocols integrating CTA and stress-rest perfusion detect functionally significant CAD with similar accuracy as CMR-Perf. Both approaches yield a very good accuracy. Integration of CTP and CTA improves MDCT performance for the detection of relevant CAD in intermediate to high pre-test probability populations.
An unexpected regioselectivity reversal was observed in the synthesis of vinylgold(I) complexes from propargyl carboxamides. The use of Au(IPr)(OH) affords preferentially vinylgold(I) complexes ...resulting from a 5-exo-dig cyclization, whereas the use Au(IPr)+ species, generated in situ starting from Au(IPr)(Cl) and AgOTf, leads to vinylgold(I) complexes which form via a 6-endo-dig cyclization, This unexpected “selectivity switch” for this cyclization led us to propose two different reaction pathways enabling the formation of the two different products. One mechanism involves the Au(IPr)+ species with “classical” π activation of the alkyne framework of the carboxamides, and the second represents an “unusual” use of the basic Brønsted character of Au(IPr)(OH). Mechanistic and DFT studies support the mechanistic hypotheses.
Objectives The aim of this study was to compare fully quantitative cardiovascular magnetic resonance (CMR) and positron emission tomography (PET) myocardial perfusion and myocardial perfusion reserve ...(MPR) measurements in patients with coronary artery disease (CAD). Background Absolute quantification of myocardial perfusion and MPR with PET have proven diagnostic and prognostic roles in patients with CAD. Quantitative CMR perfusion imaging has been established more recently and has been validated against PET in normal hearts. However, there are no studies comparing fully quantitative CMR against PET perfusion imaging in patients with CAD. Methods Forty-one patients with known or suspected CAD prospectively underwent quantitative13 N-ammonia PET and CMR perfusion imaging before coronary angiography. Results The CMR-derived MPR (MPRCMR ) correlated well with PET-derived measurements (MPRPET ) (r = 0.75, p < 0.0001). MPRCMR and MPRPET for the 2 lowest scoring segments in each coronary territory also correlated strongly (r = 0.79, p < 0.0001). Absolute CMR perfusion values correlated significantly, but weakly, with PET values both at rest (r = 0.32; p = 0.002) and during stress (r = 0.37; p < 0.0001). Area under the receiver-operating characteristic curve for MPRPET to detect significant CAD was 0.83 (95% confidence interval: 0.73 to 0.94) and for MPRCMR was 0.83 (95% confidence interval: 0.74 to 0.92). An MPRPET ≤1.44 predicted significant CAD with 82% sensitivity and 87% specificity, and MPRCMR ≤1.45 predicted significant CAD with 82% sensitivity and 81% specificity. Conclusions There is good correlation between MPRCMR and MPRPET. For the detection of significant CAD, MPRPET and MPRCMR seem comparable and very accurate. However, absolute perfusion values from PET and CMR are only weakly correlated; therefore, although quantitative CMR is clinically useful, further refinements are still required.
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