The clinical assessment of microvascular pathologies (in diabetes and in inflammatory skin diseases, for example) requires the visualization of superficial vascular anatomy. Photoacoustic tomography (PAT) scanners based on an all-optical Fabry-Perot ultrasound sensor can provide highly detailed 3D microvascular images, but minutes-long acquisition times have precluded their clinical use. Here we show that scan times can be reduced to a few seconds and even hundreds of milliseconds by parallelizing the optical architecture of the sensor readout, by using excitation lasers with high pulse-repetition frequencies and by exploiting compressed sensing. A PAT scanner with such fast acquisition minimizes motion-related artefacts and allows for the volumetric visualization of individual arterioles, venules, venous valves and millimetre-scale arteries and veins to depths approaching 15 mm, as well as for dynamic 3D images of time-varying tissue perfusion and other haemodynamic events. In exploratory case studies, we used the scanner to visualize and quantify microvascular changes associated with peripheral vascular disease, skin inflammation and rheumatoid arthritis. Fast all-optical PAT may prove useful in cardiovascular medicine, oncology, dermatology and rheumatology.
The activity of the light-oxygen-voltage/helix-turn-helix (LOV-HTH) photoreceptor EL222 is regulated through protein-protein and protein-DNA interactions, both triggered by photo-excitation of its flavin mononucleotide (FMN) cofactor. To gain molecular-level insight into the photocycle of EL222, we applied complementary methods: macromolecular X-ray crystallography (MX), nuclear magnetic resonance (NMR) spectroscopy, optical spectroscopies (infrared and UV-visible), molecular dynamics/metadynamics (MD/metaD) simulations, and protein engineering using noncanonical amino acids. Kinetic experiments provided evidence for two distinct EL222 conformations (lit1 and lit2) that become sequentially populated under illumination. These two lit states were assigned to covalently bound N5 protonated, and noncovalently bound hydroquinone forms of FMN, respectively. Only subtle structural differences were observed between the monomeric forms of all three EL222 species (dark, lit1, and lit2). While the dark state is largely monomeric, both lit states undergo monomer-dimer exchange. Furthermore, molecular modeling revealed differential dynamics and interdomain separation times arising from the three FMN states (oxidized, adduct, and reduced). Unexpectedly, all three EL222 species can associate with DNA, but only upon blue-light irradiation, a high population of stable complexes is obtained. Overall, we propose a model of EL222 activation where photoinduced changes in the FMN moiety shift the population equilibrium toward an open conformation that favors self-association and DNA-binding.
- MeSH
- Bacterial Proteins chemistry metabolism MeSH
- DNA-Binding Proteins chemistry metabolism MeSH
- DNA * chemistry metabolism MeSH
- Flavin Mononucleotide * chemistry metabolism MeSH
- Flavins chemistry metabolism MeSH
- Kinetics MeSH
- Protein Conformation MeSH
- Crystallography, X-Ray MeSH
- Oxidation-Reduction * MeSH
- Molecular Dynamics Simulation MeSH
- Light * MeSH
- Thermosynechococcus metabolism MeSH
- Transcription Factors metabolism chemistry MeSH
- Protein Binding MeSH
- Publication type
- Journal Article MeSH
STUDY DESIGN: A psychometric study. OBJECTIVES: To introduce a novel simple tool designed to evaluate the intensity of the phasic (dynamic) component of spastic motor behavior in spinal cord injury (SCI) people and to assess its reliability and validity. SETTING: The study was developed in the Spinal Cord Unit at University Hospital Motol and Paraple Centre in Prague, Czech Republic. METHODS: The Muscle Excitability Scale (MES) is designed to rate muscle motor response to exteroceptive and proprioceptive stimuli. The impairment rating ranges from zero muscle/muscle group spasm or clonus to generalized spastic response. The selected 0 to 4 scale allows for comparing the MES results with those of the Modified Ashworth Scale (MAS). After long-term use and repeated revisions, a psychometric analysis was conducted. According to the algorithm, two physiotherapists examined 50 individuals in the chronic stage after SCI. RESULTS: The inter-rater reliability of MES for both legs showed κ = 0.52. The intra-rater reliability of MES for both legs showed κ = 0.50. The inter-rater reliability of simultaneously assessed MAS for both legs was higher, with κ = 0.69. The intra-rater reliability of MAS for both legs showed κ = 0.72. Spearman's rank correlation coefficient between MES and spasm frequency of Penn Spasm Frequency Scale (PSFS) was low, while the correlation coefficient between MES and the severity part of PSFS was moderate. CONCLUSIONS: The MES is a complementary tool for assessing the dynamic component of spastic motor behavior in SCI people. It allows a more comprehensive clinical characterization of spastic reflexes when used along with the MAS.
- MeSH
- Adult MeSH
- Muscle, Skeletal physiopathology MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Spinal Cord Injuries * physiopathology diagnosis complications MeSH
- Psychometrics * MeSH
- Reproducibility of Results MeSH
- Aged MeSH
- Severity of Illness Index MeSH
- Muscle Spasticity * physiopathology diagnosis etiology MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Young Adult MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
In this study, the vibrational characteristics of optically excited echinenone in various solvents and the Orange Carotenoid Protein (OCP) in red and orange states are systematically investigated through steady-state and time-resolved spectroscopy techniques. Time-resolved experiments, employing both Transient Absorption (TA) and Femtosecond Stimulated Raman Spectroscopy (FSRS), reveal different states in the OCP photoactivation process. The time-resolved studies indicate vibrational signatures of exited states positioned above the S1 state during the initial 140 fs of carotenoid evolution in OCP, an absence of a vibrational signature for the relaxed S1 state of echinenone in OCP, and more robust signatures of a highly excited ground state (GS) in OCP. Differences in S1 state vibration population signatures between OCP and solvents are attributed to distinct conformations of echinenone in OCP and hydrogen bonds at the keto group forming a short-lived intramolecular charge transfer (ICT) state. The vibrational dynamics of the hot GS in OCP show a more pronounced red shift of ground state CC vibration compared to echinenone in solvents, thus suggesting an unusually hot form of GS. The study proposes a hypothesis for the photoactivation mechanism of OCP, emphasizing the high level of vibrational excitation in longitudinal stretching modes as a driving force. In conclusion, the comparison of vibrational signatures reveals unique dynamics of energy dissipation in OCP, providing insights into the photoactivation mechanism and highlighting the impact of the protein environment on carotenoid behavior. The study underscores the importance of vibrational analysis in understanding the intricate processes involved in early phase OCP photoactivation.
T-tubules (TT) form a complex network of sarcolemmal membrane invaginations, essential for well-co-ordinated excitation-contraction coupling (ECC) and thus homogeneous mechanical activation of cardiomyocytes. ECC is initiated by rapid depolarization of the sarcolemmal membrane. Whether TT membrane depolarization is active (local generation of action potentials; AP) or passive (following depolarization of the outer cell surface sarcolemma; SS) has not been experimentally validated in cardiomyocytes. Based on the assessment of ion flux pathways needed for AP generation, we hypothesize that TT are excitable. We therefore explored TT excitability experimentally, using an all-optical approach to stimulate and record trans-membrane potential changes in TT that were structurally disconnected, and hence electrically insulated, from the SS membrane by transient osmotic shock. Our results establish that cardiomyocyte TT can generate AP. These AP show electrical features that differ substantially from those observed in SS, consistent with differences in the density of ion channels and transporters in the two different membrane domains. We propose that TT-generated AP represent a safety mechanism for TT AP propagation and ECC, which may be particularly relevant in pathophysiological settings where morpho-functional changes reduce the electrical connectivity between SS and TT membranes. KEY POINTS: Cardiomyocytes are characterized by a complex network of membrane invaginations (the T-tubular system) that propagate action potentials to the core of the cell, causing uniform excitation-contraction coupling across the cell. In the present study, we investigated whether the T-tubular system is able to generate action potentials autonomously, rather than following depolarization of the outer cell surface sarcolemma. For this purpose, we developed a fully optical platform to probe and manipulate the electrical dynamics of subcellular membrane domains. Our findings demonstrate that T-tubules are intrinsically excitable, revealing distinct characteristics of self-generated T-tubular action potentials. This active electrical capability would protect cells from voltage drops potentially occurring within the T-tubular network.
BACKGROUND: Despite the increasing number of research studies examining the effects of age on the control of posture, the number of annual fall-related injuries and deaths continues to increase. A better understanding of how old age affects the neural mechanisms of postural control and how countermeasures such as balance training could improve the neural control of posture to reduce falls in older individuals is therefore necessary. The aim of this review is to determine the effects of age on the neural correlates of balance skill learning measured during static (standing) and dynamic (walking) balance tasks in healthy individuals. METHODS: We determined the effects of acute (1-3 sessions) and chronic (> 3 sessions) balance skill training on balance in the trained and in untrained, transfer balance tasks through a systematic review and quantified these effects by robust variance estimation meta-analysis in combination with meta-regression. We systematically searched PubMed, Web of Science, and Cochrane databases. Balance performance and neural plasticity outcomes were extracted and included in the systematic synthesis and meta-analysis. RESULTS: Forty-two studies (n = 622 young, n = 699 older individuals) were included in the systematic synthesis. Seventeen studies with 508 in-analysis participants were eligible for a meta-analysis. The overall analysis revealed that acute and chronic balance training had a large effect on the neural correlates of balance skill learning in the two age groups combined (g = 0.79, p < 0.01). Both age groups similarly improved balance skill performance in 1-3 training sessions and showed little further improvements with additional sessions. Improvements in balance performance mainly occurred in the trained and less so in the non-trained (i.e., transfer) balance tasks. The systematic synthesis and meta-analysis suggested little correspondence between improved balance skills and changes in spinal, cortical, and corticospinal excitability measures in the two age groups and between the time courses of changes in balance skills and neural correlates. CONCLUSIONS: Balance skill learning and the accompanying neural adaptations occur rapidly and independently of age with little to no training dose-dependence or correspondence between behavioral and neural adaptations. Of the five types of neural correlates examined, changes in only spinal excitability seemed to differ between age groups. However, age or training dose in terms of duration did not moderate the effects of balance training on the changes in any of the neural correlates. The behavioral and neural mechanisms of strong task-specificity and the time course of skill retention remain unclear and require further studies in young and older individuals. REGISTRATION: PROSPERO registration number: CRD42022349573.
- Publication type
- Systematic Review MeSH
Úvod: Turnerův syndrom (TS) je spojen s řadou jasně definovaných kardiovaskulárních rizik v podobě vrozených srdečních vad a získaných kardiovaskulárních onemocnění. Nejednotné jsou údaje o arytmogenním potenciálu u nositelek TS, především ve výskytu maligních komorových arytmií na podkladě dlouhého intervalu QT. Cílem této práce bylo zhodnocení výskytu abnormalit EKG u pacientek s tímto syndromem. Metodika: Do studie bylo zařazeno 61 dívek a žen s TS, u kterých bylo provedeno kompletní kardiologické vyšetření včetně EKG a holterovské monitorace EKG. Na 12svodovém EKG byla hodnocena délka intervalu PR a QT, při holterovské monitoraci EKG průměrná tepová frekvence (TF) včetně z-score, přítomnost síňové/komorové extrasystolie a jiných arytmií. Interval QT byl korigován dle Bazetta a Hodgese a tyto hodnoty byly porovnány. Analyzována byla závislost parametrů na jednotlivých karyotypech. Výsledky: Medián intervalu PR byl 120 ms (průměr 118,4 ms), krátký interval PR byl identifikován u 13 % (8/61), žádná z pacientek neměla delta vlnu jako obraz preexcitace komor. Absolutní hodnota QT byla v mediánu 340 ms (průměr 336 ms). Interval QTc prodloužený nad 440 ms mělo 5 % (3/61) pacientek při užití korekce dle Bazetta a 3 % (2/61) při korekci dle Hodgese. Hodnota QTc dle Bazetta se významně lišila od QTc dle Hodgese (medián 410 ms, průměr 405 ms vs. medián 390 ms, průměr 390 ms; p < 0,001). Z holterovské monitorace byla TF za 24 hodin v mediánu 92/min (průměr 93,3/min). TF nad +2 z-score se potvrdila u 6,5 % (4/61) případů. U 48 % (29/61) pacientek byla zachycena síňová a u 25 % (15/61) komorová extrasystolie, četnější výskyt byl u monosomie 45,X na rozdíl od ostatních skupin karyotypů. Závažné arytmie nebyly identifikovány. Závěr: EKG změny jsou u nositelek TS srovnatelně četné jako v obecné populaci a jsou klinicky nevýznamné. Riziko maligních arytmií nebylo v této studii prokázáno. Pro hodnocení intervalu QTc u pacientek s TS je pravděpodobně vhodnější metoda dle Hodgese než běžně používaná Bazettova formule.
Introduction: Turner syndrome (TS) is associated with a range of distinct cardiovascular risks such as congenital heart disease and acquired cardiovascular disease. Data on arrhythmogenic potential in TS carriers are inconsistent, especially regarding the occurrence of malignant ventricular arrhythmias due to long QT interval. The aim of this study was to evaluate the prevalence of ECG abnormalities in patients with TS. Methods: 61 girls and women with TS syndrome were included in the study and underwent a cardiac examination including ECG and 24-hour ECG Holter monitoring. The 12-lead ECG was used to assess the length of PR and QT interval, the mean heart rate (HR) including z-score, presence of atrial/ventricular premature beats and other arrhythmias. QT interval was corrected according to Bazett and Hodges formulas, and both values were statistically compared. The relationship of parameters to individual karyotypes was analyzed. Results: Median PR interval was 120 ms (mean 118.4 ms), short PR interval was identified in 13% (8/61), none of the patients had delta wave as a manifestation of ventricular pre-excitation. Median of absolute QT values was 340 ms (mean 336 ms). QTc interval prolonged above 440 ms was observed in 5% (3/61) of patients using Bazett, and 3% (2/61) using Hodges formula. The QTc value according to Bazett significantly differed from the QTc according to Hodges (median 410 ms, mean 405 ms vs. median 390 ms, mean 390 ms; p <0.001). Regarding Holter monitoring, the median 24-hour HR was 92/min (mean 93.3/min). HR above +2 z-score was confirmed in 6.5% (4/61) of cases. Atrial and ventricular premature beats were detected in 48% (29/61) and 25% (15/61) of patients, respectively, with the highest frequency in monosomy 45.X. No clinically relevant arrhythmias were identified. Conclusions: ECG changes in TS individuals are as frequent as in the general population and are clinically insignificant. The increased risk of malignant arrhythmias was not demonstrated in this study. The Hodges formula seems to be more appropriate than the widely used Bazett formula for the evaluation of the QTc interval in TS patients.
- MeSH
- Diagnostic Techniques, Cardiovascular MeSH
- Electrocardiography, Ambulatory methods MeSH
- Clinical Studies as Topic MeSH
- Humans MeSH
- Arrhythmias, Cardiac * etiology MeSH
- Long QT Syndrome etiology etiology MeSH
- Turner Syndrome * genetics complications pathology MeSH
- Heart Defects, Congenital etiology genetics MeSH
- Check Tag
- Humans MeSH
- Female MeSH
Molecules of fluorescent proteins (FPs) exhibit distinct optical directionality. This optical directionality is characterized by transition dipole moments (TDMs), and their orientation with respect to the molecular structures. Although our recent observations of FP crystals allowed us to determine the mean TDM directions with respect to the framework of representative FP molecules, the dynamics of TDM orientations within FP molecules remain to be ascertained. Here we describe the results of our investigations of the dynamics of TDM directions in the fluorescent proteins eGFP, mTurquoise2 and mCherry, through time-resolved fluorescence polarization measurements and microsecond time scale all-atom molecular dynamics (MD) simulations. The investigated FPs exhibit initial fluorescence anisotropies (r0) consistent with significant differences in the orientation of the excitation and emission TDMs. However, based on MD data, we largely attribute this observation to rapid (sub-nanosecond) fluorophore motions within the FP molecular framework. Our results allow improved determinations of orientational distributions of FP molecules by polarization microscopy, as well as more accurate interpretations of fluorescence resonance energy transfer (FRET) observations.
Experimental and theoretical foundations for femtosecond time-resolved circular dichroism (TRCD) spectroscopy of excitonic systems are presented. In this method, the system is pumped with linearly polarized light and the signal is defined as the difference between the transient absorption spectrum probed with left and with right circularly polarized light. We present a new experimental setup with a polarization grating as key element to generate circularly polarized pulses. Herein the positive (negative) first order of the diffracted light is left-(right-)circularly polarized and serves as a probe pulse in a TRCD experiment. The grating is capable of transferring ultrashort broadband pulses ranging from 470 nm to 720 nm into two separate beams with opposite ellipticity. By applying a specific chopping scheme we can switch between left and right circular polarizations and detect transient absorption (TA) and TRCD spectra on a shot-to-shot basis simultaneously. We perform experiments on a squaraine polymer, investigating excitonic dynamics, and we develop a general theory for TRCD experiments of excitonically coupled systems that we then apply to describe the experimental data in this particular example. At a magic angle of 54.7° between the pump-pulse polarization and the propagation direction of the probe pulse, the TRCD and TA signals become particularly simple to analyze, since the orientational average over random orientations of complexes factorizes into that of the interaction with the pump and the probe pulse, and the intrinsic electric quadrupole contributions to the TRCD signal average to zero for isotropic samples. Application of exciton theory to linear absorption and to linear circular dichroism spectra of squaraine polymers reveals the presence of two fractions of polymer conformations, a dominant helical conformation with close interpigment distances that are suggested to lead to short-range contributions to site energy shifts and excitonic couplings of the squaraine molecules, and a fraction of unfolded random coils. Theory demonstrates that TRCD spectra of selectively excited helices can resolve state populations that are practically invisible in TA spectroscopy due to the small dipole strength of these states. A qualitative interpretation of TRCD and TA spectra in the spectral window investigated experimentally is offered. The 1 ps time component found in these spectra is related to the slow part of exciton relaxation obtained between states of the helix in the low-energy half of the exciton manifold. The dominant 140 ps time constant reflects the decay of excited states to the electronic ground state.
- Publication type
- Journal Article MeSH
BACKGROUND: Electrographic flow (EGF) mapping enables the dynamic detection of functional or active atrial fibrillation (AF) sources outside the pulmonary veins (PVs), and the presence or absence of these sources offers a novel framework for classifying and treating persistent AF patients based on the underlying pathophysiology of their AF disease. OBJECTIVE: The primary objective of the FLOW-AF trial is to evaluate the reliability of the EGF algorithm technology (Ablamap software) to identify AF sources and guide ablation therapy in patients with persistent AF. METHODS: The FLOW-AF trial (NCT04473963) is a prospective, multicenter, randomized clinical study in which patients with persistent or long-standing persistent AF who have failed prior PV isolation (PVI) undergo EGF mapping after confirmation of intact PVI. In total, 85 patients will be enrolled and stratified based on the presence or absence of EGF-identified sources. Patients with an EGF-identified source above the predetermined activity threshold of ≥26.5% will be randomized in a 1:1 fashion to PVI only vs PVI + ablation of EGF-identified extra-PV sources of AF. RESULTS: The primary safety endpoint is freedom from serious adverse events related to the procedure through 7 days following the randomization procedure; and the primary effectiveness endpoint is the successful elimination of significant sources of excitation with the target parameter the activity of the leading source. CONCLUSIONS: The FLOW-AF trial is a randomized study designed to evaluate the ability of the EGF mapping algorithm to identify patients with active extra-PV AF sources.
- Publication type
- Journal Article MeSH
