Prolonged Relaxation Time Research Articles

Nanoscale imaging of rat atrial myocytes by scanning ion conductance microscopy reveals heterogeneity of T-tubule openings and ultrastructure of the cell membrane.

In contrast to ventricular myocytes, the structural and functional importance of atrial transverse tubules (T-tubules) is not fully understood. Therefore, we investigated the ultrastructure of T-tubules of living rat atrial myocytes in comparison with ventricular myocytes. Nanoscale cell surface imaging by scanning ion conductance microscopy (SICM) was accompanied by confocal imaging of intracellular T-tubule network, and the effect of removal of T-tubules on atrial excitation-contraction coupling (EC-coupling) was observed. By SICM imaging, we classified atrial cell surface into 4 subtypes. About 38% of atrial myocytes had smooth cell surface with no clear T-tubule openings and intracellular T-tubules (smooth-type). In 33% of cells, we found a novel membrane nanostructure running in the direction of cell length and named it 'longitudinal fissures' (LFs-type). Interestingly, T-tubule openings were often found inside the LFs. About 17% of atrial cells resembled ventricular myocytes, but they had smaller T-tubule openings and a lower Z-groove ratio than the ventricle (ventricular-type). The remaining 12% of cells showed a mixed structure of each subtype (mixed-type). The LFs-, ventricular-, and mixed-type had an appreciable amount of reticular form of intracellular T-tubules. Formamide-induced detubulation effectively removed atrial T-tubules, which was confirmed by both confocal images and decreased cell capacitance. However, the LFs remained intact after detubulation. Detubulation reduced action potential duration and L-type Ca2+ channel (LTCC) density, and prolonged relaxation time of the myocytes. Taken together, we observed heterogeneity of rat atrial T-tubules and membranous ultrastructure, and the alteration of atrial EC-coupling by disruption of T-tubules.

Multiparametric MRI characterization of knee articular cartilage and subchondral bone shape in collegiate basketball players.

Magnetic resonance imaging (MRI) is commonly used to evaluate the morphology of the knee in athletes with high‐knee impact; however, complex repeated loading of the joint can lead to biochemical and structural degeneration that occurs before visible morphological changes. In this study, we utilized multiparametric quantitative MRI to compare morphology and composition of articular cartilage and subchondral bone shape between young athletes with high‐knee impact (basketball players; n = 40) and non‐knee impact (swimmers; n = 25). We implemented voxel‐based relaxometry to register all cases to a single reference space and performed a localized compositional analysis of T 1ρ‐ and T 2‐relaxation times on a voxel‐by‐voxel basis. Additionally, statistical shape modeling was employed to extract differences in subchondral bone shape between the two groups. Evaluation of cartilage composition demonstrated a significant prolongation of relaxation times in the medial femoral and tibial compartments and in the posterolateral femur of basketball players in comparison to relaxation times in the same cartilage compartments of swimmers. The compositional analysis also showed depth‐dependent differences with prolongation of the superficial layer in basketball players. For subchondral bone shape, three total modes were found to be significantly different between groups and related to the relative sizes of the tibial plateaus, intercondylar eminences, and the curvature and concavity of the patellar lateral facet. In summary, this study identified several characteristics associated with a high‐knee impact which may expand our understanding of local degenerative patterns in this population.

Decelerated Hot Carrier Cooling in Graphene via Nondissipative Carrier Injection from MoS2.

One key to improve the performance of advanced optoelectronic devices and energy harvesting in graphene is to understand the predominant carrier scattering via optical phonons. Nevertheless, low light absorbance in graphene yields a limited photoexcited carrier density, hampering the hot carrier effect, which is strongly correlated to the hot optical phonon bottleneck effect as the energy-loss channel. Here, by integrating graphene with monolayer MoS2 possessing stronger light absorbance, we demonstrate an efficient interfacial hot carrier transfer between graphene and MoS2 in their heterostructure with a prolonged relaxation time using broadband transient differential transmittance spectroscopy. We observe that the carrier relaxation time of graphene in the heterostructure is 4 times slower than that of bare graphene. This is explained by nondissipative interlayer transfer from MoS2 to graphene, which is attributed to the enhanced hot optical phonon bottleneck effect of graphene in the heterostructure by an increased photoexcited carrier population. A significant reduction of both amplitude and relaxation time in A- and B-excitons is another evidence of the interlayer transfer from MoS2 to graphene. The nondissipative interlayer charge transfer from MoS2 to graphene is confirmed by density functional calculations. This provides a different platform to further study the photoinduced hot carrier effect in graphene heterostructures for photothermoelectric detectors or hot carrier solar cells.

Abstract MP113: Protein Hyperacetylation Mediates Bradyarrhythmia in Mice With Mitochondrial Disease

Background: Mice with germline mutation of the mitochondrial respiratory complex I subunit Ndufs4 exhibit progressive neurodegenerative phenotypes resembling Leigh syndrome (LS). Cardiomyocyte-specific Ndufs4 -/- mice demonstrate protein hyperacetylation and accelerated heart failure in response to pressure overload. Methods and Results: LS mice developed bradyarrhythmia with heart rate <400 bpm. EKG showed sick sinus syndrome (SSS) and high degree AV block. Supplementation of Nicotinamide Riboside (NR), which increased cellular NAD + , significantly reduced arrhythmia events and restored normal sinus rhythm, as shown by confocal scanning of sinoatrial nodal tissue dissected from LS mouse hearts. Immunoprecipitation and immunohistochemistry using antibody specific for K1479 of Nav 1.5 showed hyperacetylation of LS SA nodal tissue, which was attenuated by NR. HEK293-cells deficient in mitochondrial complex I subunit Ndufs2 had higher DCFDA (ROS) and lower TMRM intensity (mitochondrial membrane potential) compared with Ndufs4 knock-out cells. Ndufs2-knock-out HEK293 cells transfected with wild-type Nav 1.5 showed hyperacetylation of K1479 of Nav 1.5 . Patch clamp showed significantly reduced sodium current (I Na ) in Ndufs2 deficient HEK293 cells. NR prevented the decrease of I Na in Ndufs2 KO cells. HEK293 cells expressing mutant Nav 1.5 constructs mimicking deacetylation (K1479R) had increased I Na compared with HEK293 expressing WT Nav 1.5, suggesting that acetylation status affect Nav1.5 function. Arrythmia was noted in conduction tissue specific HCN4-Ndufs4 -/- mice, suggested a cell autonomous effect leading to arrhythmia. These findings indicate that mitochondrial complex I deficiency lead to hyperacetylation of Nav 1.5 , reduction of I Na , which subsequently cause bradyarrhythmia and this can be reversed by NR. Using echocardiography, we demonstrated significant diastolic dysfunction (decreased E’/A’, prolonged isovolemic relaxation time) in LS mice, which was ameliorated by NR. The calcium transient amplitude and decay rate, an indicator of ryanodine receptor and SERCA2 functions, was significantly decreased by ~15% in LS hearts and this was mitigated by NR, concomitant with reversal of SERCA2 hyperacetylation. Conclusions: Despite normal cardiac structure and systolic function, LS mice showed SSS, high degree AV block and diastolic dysfunction, which is mediated by hyperacetylation of Nav 1.5 and SERCA2, respectively. NR significantly reversed both arrhythmia and diastolic dysfunction. Our study demonstrates novel mechanistic link between mitochondrial complex I deficiency and the function of Nav 1.5 and SERCA2.

Patients with moderate chronic kidney disease without heart disease have reduced coronary flow velocity reserve.

AimsThe overall aim was to identify sub‐clinical cardiac abnormalities by echocardiography in patients with chronic kidney disease (CKD) stages 3 and 4 and to investigate underlying mechanisms.Methods and resultsNinety‐one patients with CKD stages 3 and 4, without a diagnosis of heart disease, and 41 healthy matched controls were included in this cross‐sectional study. Cardiac morphology and function were analysed with Doppler echocardiography and coronary flow velocity reserve (CFVR) in response to adenosine was measured in the left anterior descendent artery to detect coronary microvascular dysfunction (CMD). All study subjects had a left ventricular (LV) ejection fraction > 50%. Patients with CKD showed statistically significant increases in left atrial volume index and transmitral and pulmonary vein flow velocities during atrial contraction and prolonged LV isovolumetric relaxation time. Patients with CKD had significantly reduced CFVR vs. controls (2.74 ± 0.86 vs. 3.40 ± 0.89, P < 0.001), and 43% of patients were classified as having CMD compared with 9% of controls (P = 0.001).ConclusionsPatients with CKD stages 3 and 4, without a diagnosis of heart disease, showed early abnormalities in LV diastolic function that did not fulfil the criteria for LV dysfunction according to current guidelines. A large proportion of CKD patients had CMD, suggesting that microvascular abnormalities may have a pathogenic role in the development of heart failure in this patient group.

Ibudilast, a Phosphodiesterase Inhibitor and Toll-Like Receptor-4 Antagonist, Improves Hemorrhagic Shock and Reperfusion-Induced Left Ventricular Dysfunction by Reducing Myocardial Tumor Necrosis Factor α

ObjectivesRapid loss of blood volume causes ischemic injury to myocardial cells and impairs cardiac function. Subsequent reperfusion, although necessary to revitalize stunned tissues, can induce production of reactive oxygen species and inflammation, causing further tissue damages and weakening cardiac function. Ibudilast, a Toll-like receptor-4 (TLR4) antagonist and an inhibitor of phosphodiesterase-4, possesses antioxidative and anti-inflammatory capacities. In this study, we aim to examine the protective efficacy of ibudilast against hemorrhagic shock and reperfusion (HSR)-induced myocardial injury and cardiac dysfunction. MethodsStudies were conducted on male Sprague-Dawley rats in 3 groups: sham-operated, HSR with, and HSR without pretreatment of ibudilast. Hemorrhagic shock was induced by withdrawing blood from the femoral artery until the mean aortic pressure dropped to around 40 mm Hg; reperfusion was conducted by replenishing blood after 120 minutes of hemorrhagic shock, and the observation continued for another 240 minutes. The left ventricular (LV) contractility, diastolic suction capacity, and ventricular stiffness were evaluated using simultaneous LV pressure, and volume was recorded during a temporary inferior vena cava constriction at the end of reperfusion. Ibudilast (10 mg/kg) was administered intraperitoneally 3 days and 20 minutes prior to HSR. Serum creatine kinase myocardial band (CK-MB) was examined at the end of both HSR, and serum CK-MB, myocardial TLR4 protein expression, and malondialdehyde (MDA) and tumor necrosis factor (TNF)-α levels at the end of reperfusion. ResultsHSR induced an increase in serum CK-MB. Subsequent reperfusion further increased serum CK-MB, upregulated myocardial TLR4 protein expression, and increased tissue levels MDA and TNF-α vs the sham (P < .05). HSR reduced LV contractility, prolonged LV relaxation time, and increased LV diastolic stiffness. Ibudilast pretreatment attenuated HSR-induced TLR4 protein expression, reduced myocardial MDA and TNF-α levels, and protected against cardiac dysfunction. ConclusionsIbudilast pretreatment reduced myocardial TLR4 expression, decreased MDA and TNF-α levels, and protected against HSR-induced decrease in LV contractility, prolonged LV relaxation time, and increased diastolic stiffness.

Diagnosis of lumbar radiculopathy using simultaneous MR neurography and apparent T2 mapping

We sought to assess the utility of simultaneous apparent T2 mapping and neurography with the nerve-sheath signal increased by inked rest-tissue rapid acquisition of relaxation-enhancement imaging (SHINKEI-Quant) for the quantitative evaluation of compressed nerves in patients with lumbar radiculopathy.Thirty-two patients with lumbar radiculopathy and 5 healthy subjects underwent simultaneous apparent T2 mapping and neurography with SHINKEI-Quant. Regions of interest (ROIs) were placed in the lumbar dorsal root ganglia (DRG) and the spinal nerves distal to the lumbar nerves bilaterally at L4-S1. The T2 relaxation times were measured on the affected and unaffected sides. The T2 ratio was calculated as the affected side/unaffected side. Pearson correlation coefficients were calculated to determine the correlation between the T2 relaxation times or T2 ratio and clinical symptoms. An ROC curve was used to examine the diagnostic accuracy and threshold of the T2 relaxation times and T2 ratio.We observed no significant differences in the T2 relaxation times between the nerve roots on the left and right at each spinal level in healthy subjects. In patients, lumbar neurography revealed swelling of the involved nerve, and prolonged T2 relaxation times compared with that of the contralateral nerve. The T2 ratio correlated with leg pain. The ROC analysis revealed that the T2 relaxation time threshold was 127 ms and the T2 ratio threshold was 1.07.To our knowledge, this is the first study to show the utility of SHINKEI-Quant for the quantitative evaluation of lumbar radiculopathy.

Use of Cells from Remotely Collected Urine to Generate Human Induced Pluripotent Stem Cells and Myofibers that Recapitulate Unconventional Myopathies

Mutations in embryonic myosin (MYH3) disrupt the function of skeletal muscle early in fetal development resulting in congenital contractures of multiple body areas, most commonly the hands and feet. In the most severe condition, Freeman-Sheldon Syndrome (FSS), muscles of the face and back are also involved. Study of the mechanism(s) underlying formation of contractures, as well as development of targeted therapeutics for contractures, are severely limited by the difficulty of obtaining skeletal muscle from affected individuals. Innovative approaches are therefore needed to model disease mechanisms and test therapeutics that could improve clinical outcomes. We show that urine collected at home can be used to harvest cells for reprogramming into induced pluripotent stem cells (iPSCs) and then differentiated into spontaneously contracting skeletal muscle. We identified individuals (ages 12-50 years) with the most common MYH3 mutations, p.R672C, p.R672H, and p.T178I, in underlying FSS. Kits were sent to each person to collect their first morning-voided urine and this sample was returned to us overnight. Somatic cells were extracted from the urine and reprogrammed using a CytoTune 2.0 Sendai kit. The iPSC lines have a normal karyotype, express common pluripotency markers, and maintain the original MYH3 mutations. Cells were successfully reprogrammed in all three persons tested. Preliminary functional studies using individual contractile organelles (myofibrils) show that mutant cells have reduced contractile force and prolonged relaxation times. Myofibers (cells) loaded with Fluo4 AM calcium dye displayed delayed calcium reuptake during relaxation. These findings validate our approach to reprogramming and muscle differentiation, yielding myogenic cells that recapitulate the disease phenotype identified in myofibers sampled from affected individuals. Moreover, these myogenic cells are now available for development and testing of therapeutics.

Enhancement of ultrafast photoluminescence from deformed graphene studied by optical localization microscopy

By using localization techniques, we demonstrated that the morphology of a 2D material in three dimensions can be optically obtained with nanometer precision in z-axis. This technique provides a convenient method to study the correlation between the optical properties and the morphology of 2D materials for the same area. We utilized optical localization microscopy to directly study the correlation between the ultrafast photoluminescence and the morphology of graphene. We observed enhancement of the ultrafast photoluminescence from the deformed graphene. In comparison to the planar graphene, the enhancement factor of ultrafast photoluminescence could be up to several times at the highly curved region. We found that the intensity of photoluminescence from the uniaxially rippled graphene depends on the polarization of excitation light. Furthermore, Raman spectroscopy was used to measure the strain distribution. Pump–probe measurements were conducted to reveal the carrier dynamics. From the experimental results, two mechanisms were confirmed to mainly account for the enhancement of ultrafast photoluminescence from the deformed graphene. One is the deformation-induced strain increases the absorption of graphene. The other is the prolonged carrier relaxation time in the curved graphene.

Simultaneous MR neurography and apparent T2 mapping of cervical nerve roots before microendoscopic surgery to treat patient with radiculopathy due to cervical disc herniation: Preliminary results

There is no imaging modality to quantitatively evaluate compressed cervical nerve roots in cervical radiculopathy. Here we sought to evaluate the usefulness of simultaneous apparent T2 mapping and neurography with nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation-enhancement imaging (SHINKEI-Quant) to evaluate compressed nerves quantitatively in patients with cervical radiculopathy due to cervical disc hernia before microendoscopic surgery.One patient with cervical radiculopathy due to cervical disc hernia before microendoscopic surgery and 5 healthy subjects underwent simultaneous apparent T2 mapping and neurography with SHINKEI-Quant. The patient was a 49-year-old man with severe right upper arm pain and numbness. Based on MRI images, we suspected right C7 radiculopathy due to C6-7 cervical disc hernia. The T2 relaxation times of the cervical dorsal root ganglia of the brachial plexus bilaterally at C5–C8 were measured.We observed no significant differences in T2 relaxation times between the nerve roots on the left and right at each spinal level with values in healthy subjects. In our patient, neurography revealed swelling of the right C7 nerve, and a prolonged T2 relaxation time compared with that of the contralateral, unaffected C7 nerve. We performed microendoscopic surgery and the symptoms improved.We were able to evaluate the injured nerve root quantitatively in a patient with cervical radiculopathy using the SHINKEI-Quant technique, being the first study to our knowledge to show the usefulness of this technique to evaluate cervical radiculopathy quantitatively before microendoscopic surgery.

Modelling diastolic dysfunction in induced pluripotent stem cell-derived cardiomyocytes from hypertrophic cardiomyopathy patients.

Diastolic dysfunction (DD) is common among hypertrophic cardiomyopathy (HCM) patients, causing major morbidity and mortality. However, its cellular mechanisms are not fully understood, and presently there is no effective treatment. Patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) hold great potential for investigating the mechanisms underlying DD in HCM and as a platform for drug discovery. In the present study, beating iPSC-CMs were generated from healthy controls and HCM patients with DD. Micropatterned iPSC-CMs from HCM patients showed impaired diastolic function, as evidenced by prolonged relaxation time, decreased relaxation rate, and shortened diastolic sarcomere length. Ratiometric Ca2+ imaging indicated elevated diastolic [Ca2+]i and abnormal Ca2+ handling in HCM iPSC-CMs, which were exacerbated by β-adrenergic challenge. Combining Ca2+ imaging and traction force microscopy, we observed enhanced myofilament Ca2+ sensitivity (measured as dF/Δ[Ca2+]i) in HCM iPSC-CMs. These results were confirmed with genome-edited isogenic iPSC lines that carry HCM mutations, indicating that cytosolic diastolic Ca2+ overload, slowed [Ca2+]i recycling, and increased myofilament Ca2+ sensitivity, collectively impairing the relaxation of HCM iPSC-CMs. Treatment with partial blockade of Ca2+ or late Na+ current reset diastolic Ca2+ homeostasis, restored diastolic function, and improved long-term survival, suggesting that disturbed Ca2+ signalling is an important cellular pathological mechanism of DD. Further investigation showed increased expression of L-type Ca2+channel (LTCC) and transient receptor potential cation channels (TRPC) in HCM iPSC-CMs compared with control iPSC-CMs, which likely contributed to diastolic [Ca2+]i overload. In summary, this study recapitulated DD in HCM at the single-cell level, and revealed novel cellular mechanisms and potential therapeutic targets of DD using iPSC-CMs.

Effect of Poly(styrene-ran-methyl acrylate) Inclusion on the Compatibility of Polylactide/Polystyrene-b-Polybutadiene-b-Polystyrene Blends Characterized by Morphological, Thermal, Rheological, and Mechanical Measurements.

A poly(styrene-ran-methyl acrylate) (S-MA) (75/25 mol/mol), synthesized by surfactant-free emulsion copolymerization, was used as a compatibilizer for polystyrene-b-polybutadiene-b-polystyrene (SBS)-toughened polylactide (PLA) blends. Upon compatibilization, the blends exhibited a refined dispersed-phase morphology, a decreased crystallinity with an increase in their amorphous interphase, improved thermal stability possibly from the thicker, stronger interfaces insusceptible to thermal energy, a convergence of the maximum decomposition-rate temperatures, enhanced magnitude of complex viscosity, dynamic storage and loss moduli, a reduced ramification degree in the high-frequency terminal region of the Han plot, and an increased semicircle radius in the Cole–Cole plot due to the prolonged chain segmental relaxation times from increases in the thickness and chain entanglement degree of the interphase. When increasing the S-MA content from 0 to 3.0 wt %, the tensile properties of the blends improved considerably until 1.0 wt %, above which they then increased insignificantly, whereas the impact strength was maximized at an optimum S-MA content of ~1.0 wt %, hypothetically due to balanced effects of the medium-size SBS particles on the stabilization of preexisting crazes and the initiation of new crazes in the PLA matrix. These observations confirm that S-MA, a random copolymer first synthesized in our laboratory, acted as an effective compatibilizer for the PLA/SBS blends.

Magnetic resonance imaging of brain cell water

In the central nervous system of vertebrates, cell bodies of neurons are often assembled as nuclei or cellular layers that play specific roles as functional units. The purpose of this work was to selectively highlight such cell assemblies by magnetic resonance imaging using signals from water protons that are associated with intracellular paramagnetic ions, while saturating lipid-associated water protons as well as extracellular free water protons. Given the significant correlation between image signal intensity and water proton density, the high signal intensities observed for such cell assemblies must be attributed to their abundant paramagnetic-ion-associated water protons. In the hippocampal formation, the technique visualized cell assemblies that were so far not depicted in human in vivo. In the brainstem, the technique delineated noradrenergic neuron groups such as the locus coeruleus in human and mice in vivo. Their reduced magnetization-transfer ratios together with their prolonged relaxation times compared to other gray matter indicate that the source of their high signal intensity is not the presence of T1-shortening molecules, e.g., neuromelanin, but their high water content. Given the general absence of neuromelanin in noradrenergic neurons of rodents, their high signal intensity in mice in vivo further supports this view.

Theory for impedance response of grain and grain boundary in solid state electrolyte

We develop a generic phenomenological theory for the electrochemical impedance response of solid state electrolytes (SSEs). The theory describes dynamics of various physical processes in grain (g) and grain boundary (gb). Leaking capacitor model for the dynamics of ions in grain accounts compositional heterogeneity, ion reorganization and transfer across the surface of the grain. Model for ion relaxation in the grain boundary is determined through generalized electric double layer (EDL) theory over heterogeneous surface (Singh and Kant, 2013). The theory accounts for ion transfer and reorganization in grain boundary has the following components: (i) ions distribution at energetically heterogeneous surface of grain; (ii) space charge layer (SCL) in the grain boundary. Predicted impedance response of SSE evinces three frequency regimes, viz. (i) high frequency regime, attributed to relaxation of ions in grain and grain boundary (SCL), (ii) intermediate frequency regime, related to ion reorganization and transfer across heterogeneous grain and grain boundary (iii) low frequency regime, ascribed to the SSE/metal interface. The model emphasizes that ions encounter energetic heterogeneity in the grain causing distribution of relaxation time with a characteristic exponent γg. Doped grain with aliovalent cations further enhances the structural/energetic heterogeneity and concentration of mobile ions therefore decreases the ion transfer resistance from grain to grain boundary. Doping also enhances the surface concentration of mobile ions at the grain boundary region resulting in enhanced capacitance and prolonged relaxation time of compact layer.

Cardiac profile of the Czech population of Duchenne muscular dystrophy patients: a cardiovascular magnetic resonance study with T1 mapping

BackgroundThe progressive cardiomyopathy that develops in boys with Duchenne and Becker muscular dystrophy (DMD/BMD) is presumed to be a secondary consequence of the fibrosis within the myocardium. There are only limited data on using parametric imaging in these patients. The purpose of this study was to assess native T1 and extracellular volume (ECV) values in DMD patients.MethodsThe Czech population of males with DMD/BMD was screened. All eligible patients fulfilling the inclusion criteria were included. Forty nine males underwent cardiac magnetic resonance (MR) examination including T1 native and post-contrast mapping measurements. One DMD patient and all BMD patients were excluded from statistical analysis. Three groups were compared – Group D1 - DMD patients without late gadolinium enhancement (LGE) (n = 23), Group D2 - DMD patients with LGE (n = 20), and Group C – gender matched controls (n = 13).ResultsCompared to controls, both DMD groups had prolonged T1 native relaxation time. These results are concordant in all 6 segments as well as in global values (1041 ± 31 ms and 1043 ± 37 ms vs. 983 ± 15 ms, both p < 0.05). Group D2 had significantly increased global ECV (0.28 ± 0.044 vs. 0.243 ± 0.013, p < 0.05) and segmental ECV in inferolateral and anterolateral segments in comparison with controls. The results were also significant after adjustment for subjects’ age.ConclusionDMD males had increased native T1 relaxation time independent of the presence or absence of myocardial fibrosis. Cardiac MR may provide clinically useful information even without contrast media administration.

Clinical efficacy of transcutaneous triamcinolone acetonide injection for upper eyelid retraction and swelling in patients with thyroid eye disease.

AimTo evaluate the efficacy of transcutaneous triamcinolone acetonide (TA) injection for the treatment of upper eyelid retraction and swelling in thyroid eye disease (TED) patients.Patients and methodsThis is a case series. Three euthyroid TED patients with features of both upper eyelid retraction and swelling were recruited. TED signs appeared within 6 months prior to treatment. Next, 0.5 mL of TA (40 mg/mL) was transcutaneously injected targeting the orbital fat around the levator palpebrae superioris (LPS) muscle. At each visit, eyelid retraction was evaluated by palpebral fissure height and the presence of scleral show above the superior corneoscleral limbus. Eyelid swelling was judged by the appearance of upper eyelid bulging and the lack of an eyelid sulcus. In addition, the LPS muscle, orbital and retro-orbicularis oculi fat were observed using MRI before and after treatment.ResultsTwo patients had resolution of their upper lid retraction and swelling within 12 months. In the other patient who had proptosis, eyelid retraction resolved, while eyelid swelling remained mild. In all cases, MRI revealed that treatment resulted in thinner LPS muscle and reduced fat swelling. In addition, both high-intensity signals on T2 images and prolonged T2 relaxation time were normalized. No adverse signs were observed.ConclusionTranscutaneous TA injection was effective as a treatment for upper eyelid retraction and swelling in euthyroid TED patients who had signs within 6 months prior to treatment. Transcutaneous TA injection induced reduction of LPS muscle enlargement and fat tissue swelling. These reductions by transcutaneous TA injection were verified using MRI.

Early myocardial changes in normotensive children of hypertensive parents: a tissue Doppler study.

The aim of this study was to examine early left ventricular systolic and diastolic changes using tissue Doppler imaging (TDI) in normotensive children of hypertensive parents (NCHP), a risk group for cardiovascular diseases. Ninety-two children characterized as NCHP (age range: 6-18 years) and 90 age-, gender-, height-, weight-, and body mass index-matched children characterized as normotensive children of normotensive parents (NCNP) were included in the study. Left ventricular diastolic parameters were assessed using transmitral flow pulse wave Doppler echocardiography and mitral septal and lateral annular TDI. Left ventricular systolic and diastolic function was evaluated globally using the TDI-derived myocardial performance index (MPI'). Mean systolic, diastolic, and average blood pressure values were found to be higher in the NCHP group than in the NCNP group. Echocardiographic parameters in the NCHP group showed statistically significant differences, including increased interventricular septum end-diastolic wall thickness (p = 0.039), left ventricular end-diastolic posterior wall thickness (p = 0.011), relative wall thickness (p = 0.013), and transmitral flow A velocity (p = 0.003); parameters determined by TDI included a prolonged isovolumetric relaxation time (p < 0.001) and isovolumetric contraction time (p = 0.002), shortened ejection time (p = 0.001), and increased MPI' (p < 0.001) in the NCHP group. Early alterations in myocardial function, indicated by increased MPI' values, had a positive correlation with systolic blood pressure and myocardial thickness. Conversely, they were negatively correlated with the ejection fraction and E/A ratio, which decreases with diastolic dysfunction. The MPI' is considered a repeatable, non-invasive, and low-cost assessment method that can surpass conventional methods in the detection of early left ventricular systolic and diastolic functional changes in the subclinical period of hypertension in children with familial risk.

Abstract 243: Modeling of Diastolic Dysfunction in Induced Pluripotent Stem Cell-derived Cardiomyocytes From Hypertrophic Cardiomyopathy Patients

Aims: Diastolic dysfunction (DD) is common among hypertrophic cardiomyopathy (HCM) patients, causing major morbidity and mortality. Yet its cellular mechanisms are not fully understood, and presently, there is no effective treatment. Patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) hold great potential for investigating the mechanisms underlying DD and as a platform for drug discovery. Methods and results: In the present study, beating iPSC-CMs were generated from healthy recruits and HCM patients with evident DD. Micropatterned iPSC-CMs from HCM patients showed impaired diastolic function, as evidenced by prolonged relaxation time, retarded relaxation rate, and shortened diastolic sarcomere length. Ratiometric Ca 2+ imaging indicated elevated diastolic [Ca 2+ ] i and abnormal Ca 2+ handling in HCM iPSC-CMs, which were exacerbated by β-adrenergic challenge. Combining Ca 2+ imaging and traction force microscopy (TFM), we observed enhanced myofilament Ca 2+ sensitivity (measured as dF/Δ[Ca 2+ ] i ) in HCM iPSC-CMs. These results indicated that cytosolic diastolic Ca 2+ overload, slowed [Ca 2+ ] i decline and increased myofilament Ca 2+ sensitivity, collectively impair the relaxation of HCM cells. Treating HCM iPSC-CMs with partial blockade of Ca 2+ or late Na + current reset diastolic Ca 2+ homeostasis, restored diastolic function and improved long-term survival, suggesting disturbed Ca 2+ signaling is an important cellular pathological mechanism of DD. Further investigation showed increased expression of L-type calcium channel (LTCC) and transient receptor potential channels (TRPCs) in HCM iPSC-CMs, which likely contribute to diastolic [Ca 2+ ] i overload. Conclusion: In summary, this study recapitulated DD at the single cell level, and revealed novel mechanisms and potential therapeutic targets of DD using HCM iPSC-CMs.

T2 relaxation times of the anterolateral femoral cartilage in patients after ACL-reconstruction with and without a deep lateral femoral notch sign

PurposeTo quantitatively assess T2 relaxation times of the anterolateral femoral cartilage following anterior cruciate ligament (ACL)-reconstruction with and without a positive deep lateral femoral notch sign (DLNS) at post-traumatic MRI. Materials and MethodsIn 52 patients post-traumatic MRI as well as 12 months after ACL-rupture (ACLR) and surgical treatment were analysed. In 28 patients a positive DLNS was present at post-traumatic MRI.For quantitative analysis, T2 relaxation time measurements (7 TE: 10–70 ms) were performed at time of re-evaluation. Three polygonal ROIs encompassing the full cartilage layer were placed in the anterolateral femoral cartilage. Clinical assessment included Lysholm-Tegner-Activity-Score, Rasmussen's clinical score and modified Cincinnati-Rating-System-Questionnaire. Description and differences were calculated as means and confidence intervals of means, controlled for the cluster effect of person, if appropriate. ResultsIn patients with a positive DLNS after ACLR, relaxation times in the notch region were significantly prolonged compared to patients without a positive DLNS (Δ 7.4 ms, CI: 5.6–9.2; p-value <0.001) as well as to the adjacent anterior (Δ 5.7 ms, CI: 4.7–6.7; p-value <0.001) and central femoral cartilage (Δ 6.6 ms, CI: 5.7–7.6; p-value <0.001).Solely insignificant differences were noticed in the performed clinical scores comparing the two groups (p > 0.05). ConclusionSignificantly prolonged T2 relaxation times of the anterolateral femoral cartilage were found in patients with a positive DLNS following ACL-reconstruction compared to patients without a DLNS. Based on these results, it has to be assumed that a positive DLNS is associated with higher cartilage degradation.

Cross-network dissemination model of public opinion in coupled networks

In a coupled network system, information can be sourced and disseminated in many ways. In this study, we investigate the diffusion effect of information in a coupled social network environment, using two new node states to augment information dissemination. Using an improved SIR model, this paper posits that a coupled network comprises two categories of nodes, independent spreaders and cross-network spreaders, which participate in the process of information spreading. The independent spreaders act as a source for information, leading to a higher spreading probability and a wider spreading scope. The cross-network spreaders transfer the spreading onto another network. Our simulation result using synthetic data suggests that the environment of the coupled social network affects the diffusion of information and information diffusion has a prolonged relaxation time due to these nodes. Further, we analyze the data collected from Weibo and WeChat of an actual news event to visualize the information spread process in the cross-network dissemination case of public opinion, and show that our improved SIR model provides a good fit to explain the data.