Overdamped mechanical model of myosin II

Due to their small size molecular systems are often overdamped and they are affected by significant fluctuations due to thermal forces. In this paper we investigate the effect of overdamping on a simple mechanical model of myosin II, the motor protein responsible for muscle contraction. We demonstrate that this model, based on the experimentally observed shape of the protein’s subdomains, is consistent with the available experimental results. We also shed new light on the debate whether the powerstroke is a sudden conformational change followed by relaxation to equilibrium or a thermal fluctuation followed by a fixation by a ratchet-like mechanism in an energetically favourable conformation: we propose that these mechanisms coexist

Spontaneous Dissection of a Septal Coronary Artery Mimicking Myocarditis

Acute chest pain and dyspnea often raise coronary disease suspicion. When echocardiography and cardiac computed tomography findings appear normal, alternative diagnoses should be explored. We present a case initially suggestive of myocarditis but later revealed as coronary dissection by cardiac magnetic resonance. This case emphasizes the role of advanced imaging in atypical cardiac presentations

Three-dimensional Whole-Heart Cardiac MRI Sequence for Measuring Trabeculation in Left Ventricular Noncompaction

PURPOSE To compare three-dimensional (3D) whole-heart MRI with isotropic submillimeter resolution with standard two-dimensional (2D) cine MRI in measuring the bilayered myocardium in left ventricular noncompaction (LVNC). MATERIALS AND METHODS Twenty-four patients with LVNC (mean age, 42 years ± 16 [SD]) were retrospectively enrolled between October 2011 and July 2020. Compacted myocardium (CM) and noncompacted myocardium (NCM) were measured in long axis (Petersen approach) and short axis (Jacquier approach) at 3D whole-heart and 2D cine MRI by two independent readers. Image quality (1 = excellent, 2 = adequate, 3 = nondiagnostic), considering discrimination between NCM and CM and CM and adjacent tissue, was evaluated. Pearson, Spearman, and intraclass correlation tests were used as statistical tests. RESULTS In long-axis measurements, the correlation between both sequences was moderate to strong for CM (Pearson, 0.66-0.79; Spearman, 0.61-0.68) and strong to very strong for NCM (Pearson, 0.90-0.97; Spearman, 0.77-0.91). Intraclass correlation coefficient (ICC) in 3D whole-heart MRI was 0.90 (95% CI: 0.78, 0.95) for CM and 0.94 (95% CI: 0.84, 0.97) for NCM, while ICC in 2D cine MRI was 0.77 (95% CI: 0.55, 0.89) for CM and 0.87 (95% CI: 0.72, 0.94) for NCM. Short-axis CM and NCM measurements had a strong to very strong correlation between both sequences (Pearson, 0.86-0.98; Spearman, 0.82-0.98). ICC in 3D whole-heart MRI was 0.96 (95% CI: 0.94, 0.99) for CM and 0.98 (95% CI: 0.97, 0.99) for NCM, while ICC in 2D cine MRI was 0.82 (95% CI: 0.63, 0.92) for CM and 0.87 (95% CI: 0.72, 0.94) for NCM. 3D whole-heart MRI demonstrated higher image quality than did 2D cine MRI (P < .001). CONCLUSION 3D whole-heart MRI revealed higher image quality, with better structure discrimination and interobserver agreement in LVNC measurements, compared with standard 2D cine images.Keywords: MR Imaging, Cardiac, Cardiovascular Magnetic Resonance, Left Ventricular Noncompaction, Free-breathing Imaging Technique Supplemental material is available for this article. © RSNA, 2022See also the commentary by Jensen and Petersen in this issue

Analitikus és kombinatórikus számelmélet = Analytical and Combinatorial Number Theory

A kutatás keretében a 4 év alatt összesen 79 tudományos dolgozat született, melynek nagy többsége erős nemzetközi folyóiratban jelent meg. Az elért eredmények közül kiemelkednek Pintz és társszerzői prímszámelméletben elért világra szóló eredményei, melyeknek igen nagy nemzetközi visszhangja van. Jelentősek Gyarmati, Sárközy és társszerzőik pszeudovéletlenséggel kapcsolatos eredményei is, melyeknek várhatóan fontos alkalmazásaik is lesznek, főként a kriptográfiában. Figyelemre méltóak Gyarmati és Sárközy véges testek feletti egyenletekre és karakterösszegekre, Ruzsa, Károlyi és társszerzőik sorozatok additív tulajdonságaira, valamint Sárközy és Szalay partíciók tulajdonságaira vonatkozó kutatásai is. | During the 4 years of the project the research resulted 79 scientific papers whose vast majority appeared in strong international journals. Outstanding results have been achieved by Pintz and his coauthors in prime number theory which are highly appreciated world wide. The results of Gyarmati, Sárközy and their coauthors on pseudorandomness are also significant, and they are expected to have important applications, mostly in cryptography. Valuable results have been achieved by Gyarmati and Sárközy on equations over finite fields and character sums, by Ruzsa, Károlyi and their coauthors on additive properties of sequences, and by Sárközy and Szalay on properties of partitions

Diagnostic performance of 3D cardiac magnetic resonance perfusion in elderly patients for the detection of coronary artery disease as compared to fractional flow reserve

OBJECTIVES: In patients of advanced age, the feasibility of myocardial ischemia testing might be limited by age-related comorbidities and falling compliance abilities. Therefore, we aimed to test the accuracy of 3D cardiac magnetic resonance (CMR) stress perfusion in the elderly population as compared to reference standard fractional flow reserve (FFR). METHODS: Fifty-six patients at age 75 years or older (mean age 79 ± 4 years, 35 male) underwent 3D CMR perfusion imaging and invasive coronary angiography with FFR in 5 centers using the same study protocol. The diagnostic accuracy of CMR was compared to a control group of 360 patients aged below 75 years (mean age 61 ± 9 years, 262 male). The percentage of myocardial ischemic burden (MIB) relative to myocardial scar burden was further analyzed using semi-automated software. RESULTS: Sensitivity, specificity, and positive and negative predictive values of 3D perfusion CMR deemed similar for both age groups in the detection of hemodynamically relevant (FFR 0.05 all). While MIB was larger in the elderly patients (15% ± 17% vs. 9% ± 13%), the diagnostic accuracy of 3D CMR perfusion was high in both elderly and non-elderly populations to predict pathological FFR (AUC: 0.906 and 0.866). CONCLUSIONS: 3D CMR perfusion has excellent diagnostic accuracy for the detection of hemodynamically relevant coronary stenosis, independent of patient age. KEY POINTS • The increasing prevalence of coronary artery disease in elderly populations is accompanied with a larger ischemic burden of the myocardium as compared to younger individuals. • 3D cardiac magnetic resonance perfusion imaging predicts pathological fractional flow reserve in elderly patients aged ≥ 75 years with high diagnostic accuracy. • Ischemia testing with 3D CMR perfusion imaging has similarly high accuracy in the elderly as in younger patients and it might be particularly useful when other non-invasive techniques are limited by aging-related comorbidities and falling compliance abilities