Strain Differences Research Articles

Investigation into the Rolling Process of 20CrNiMo/Incoloy 825 Composite Materials

This paper is focused on the rolling finite element simulation and experimental study of 20CrNiMo/Incoloy 825 composite materials. Firstly, single-pass rolling finite element simulations of the composite materials were conducted. The effects of rolling pass reduction and rolling speed on the warpage, interface strain difference, and stress of the 20CrNiMo/Incoloy 825 composite materials were evaluated, highlighting an ideal first-pass reduction of 30% and a rolling speed of 0.117 m/s. Based on these results, rolling finite element simulations under total reduction–pass conditions of 65%–3 passes, 75%–4 passes, and 85%–5 passes were conducted on 20CrNiMo/Incoloy 825 composite materials. The rolling process was found to be optimal for a total reduction of 85%–5 passes based on the ratio of the vertical compressive stress experienced by the Incoloy 825-side metal to the yield strength of Incoloy 825 at 1150 °C. Based on the results of single- and multi-pass finite element simulation experiments, microstructural observations and interface analyses were then conducted on the 20CrNiMo/Incoloy 825 composite materials after rolling. The bonding interface of the composite materials was found to be undulating, indicating good composite effects. In addition, Cr, Ni, and Fe at the interface of the composite materials exhibited a steep gradient of change, indicating trace element diffusion with a distance of 8.27 μm in the 20CrNiMo/Incoloy 825 composite materials. Finally, the interfacial bonding mechanism of the 20CrNiMo/Incoloy 825 composite materials was studied, and the results indicate that this mechanism is based on a combination of diffusion and recrystallization bonding mechanisms.

Myocardial deformation in multisystem inflammatory syndrome in children: layer-specific cardiac MRI insights from a pediatric cohort.

Multilayer strain magnetic resonance imaging (MRI) analysis offers detailed insights into myocardial mechanics and cardiac function by assessing different layers of the heart muscle, enabling a comprehensive understanding of cardiac involvement. This study aims to explore cardiac strain differences between patients with multisystem inflammatory syndrome and a control group at medium-term follow-up, utilizing a layer-specific cardiac magnetic resonance imaging (CMR) approach. In this retrospective study, patients with multisystem inflammatory syndrome in children (MIS-C) and a group of controls who had undergone cardiac magnetic resonance (CMR) imaging were selected and included. CMR was performed 30days after discharge (range 34-341days) for MIS-C patients. TrufiStrain research prototype software (Siemens Healthineers AG, Erlangen, Germany) was used for automated myocardial segmentation and strain calculation, to measure radial strain (RS), circumferential strain (CS), and longitudinal strain (LS) at the epicardial, mid-wall, and endocardial levels. Statistical analysis included Shapiro-Wilk tests, Student t-tests, and Mann-Whitney U tests, ANOVA, and regression analysis, maintaining a significance level of α = 0.05. The study cohort consisted of 32 MIS-C patients (≤ 18years; 14 females) and 64 control participants (≤ 18years; 24 females). Median interval to CMR post diagnosis was 142days (range 34-341) with normal CMR findings for all patients. The mean age of the two groups was similar (MIS-C: 14.2years; controls: 14.1years, P = 0.49). There were no significant differences in height (MIS-C: 164.7cm; controls: 163.9cm, P = 0.84), weight (MIS-C: 68.2kg; controls: 59.4kg, P = 0.11), or body surface area (MIS-C: 1.7 m2; controls: 1.7 m2, P = 0.41). Global strain measurements showed no significant differences between the groups (global LS MIS-C patients - 16.2% vs - 15.7% in controls (P = 0.23); global RS 27.8% in MIS-C patients vs 29.5% in controls (P = 0.35); and global CS - 16.7% in MIS-C patients vs - 16.8% in controls (P = 0.92)). Similarly, layer-specific strain analysis across the endocardial (LS values of - 17.7% vs - 16.8% (P = 0.19), RS of 23.1% vs 24.8% (P = 0.25), and CS of - 19.9% vs - 19.9% (P = 0.92)), epicardial (LS - 14.9% vs - 14.5% (P = 0.31), RS of 31.2% vs 33.1% (P = 0.29), and CS of - 14.1% vs - 14.2% (P = 0.75)), and midmyocardial (LS - 16.5% vs - 16.3% (P = 0.18), RS 29.3% vs 31.8% (P = 0.31), and CS - 17.0% vs - 17.2% (P = 0.95)) levels revealed no significant disparities. The only notable finding was the reduced apical radial strain in MIS-C patients compared to controls (global RS MIS-C 12.4% vs 17.4% in controls, P = 0.03; endocardium RS MIS-C 4.9% vs 10.31% in controls, P = 0.01; epicardial RS MIS-C 17.7% vs 22.6% in controls, P = 0.02; and midmyocardium RS MIS-C 12.5% vs 17.9% in controls, P = 0.02). This study demonstrates that MIS-C does not significantly impact global or layer-specific myocardial strain values, as assessed by CMR, compared to a control group. The lower apical radial strain in MIS-C patients indicates a potential localized myocardial involvement.

Cardiac Structure and Function of Elite Australian Jockeys Compared to the General Population: An Observational Cross-Sectional Study.

Research highlights the intense physiological demands of thoroughbred racing on jockeys, with elevated heart rates and substantial oxygen uptake, confirming the rigorous physical nature of the sport, however, the cardiovascular changes resulting from the physical demands of thoroughbred racing remain unexplored in Australian jockeys. Therefore, the objective of this study was to compare measures of cardiac structure and function of professional Australian jockeys to that of the general population and to determine if there are differences in heart structure and function detected using echocardiography. Forty-six jockeys and thirty-three participants from the general population underwent two-dimensional echocardiography, which included all standard views and measurements. Each measurement was compared between groups using a Mann-Whitney U test. Groups were matched for age (jockeys (35 ± 12 years) and controls (36 ± 13 years)). Jockeys were shorter (1.64 ± 0.07m vs. 1.75 ± 0.09m, p < 0.001), lighter (56.5 ± 6.0kg vs. 74.2 ± 12.9kg, p < 0.001) and had a lower body surface area (BSA) (1.55 ± 0.17m2 vs.1.9 ± 0.2m2, p < 0.001). Jockeys had a larger absolute left ventricular (LV) end diastolic volume than the control group (120 ± 18.2ml vs.109.3 ± 29.0ml, p = 0.05) which had a larger variation when indexed for BSA (78.0 ± 12.2 ml/m2 vs. 57.5 ± 13.3 ml/m2, p < 0.001). Jockeys demonstrated a higher LV mass index (79.4 ± 18.1g/m2 vs. 64.2 ± 15.4g/m2, p < 0.001). Left atrial volume index was larger in jockeys (33.4 ± 6.5mL/m2 vs. 26.3 ± 7.0mL/m2, p < 0.001). There were no differences in global longitudinal strain (GLS) for either group overall (-19.3 ± 3.0% vs. -19.8 ± 1.6%, p = 0.52), but 17% of the jockey group demonstrated an abnormal GLS. Jockeys have adaptations to their cardiac structure and function compared to the general population. Differences could be attributed to chronic physiological demands of racing and should be considered in future research involving jockeys.

Antiviral immunity within neural stem cells distinguishes Enterovirus-D68 strain differences in forebrain organoids

Neural stem cells have intact innate immune responses that protect them from virus infection and cell death. Yet, viruses can antagonize such responses to establish neuropathogenesis. Using a forebrain organoid model system at two developmental time points, we identified that neural stem cells, in particular radial glia, are basally primed to respond to virus infection by upregulating several antiviral interferon-stimulated genes. Infection of these organoids with a neuropathogenic Enterovirus-D68 strain, demonstrated the ability of this virus to impede immune activation by blocking interferon responses. Together, our data highlight immune gene signatures present in different types of neural stem cells and differential viral capacity to block neural-specific immune induction.

Radiation damage in He irradiated nanolayered Zr/Nb at different temperatures

Nanolayered Zr/Nb metals are considered promising for advanced nuclear reactors due to their superior resistance to irradiation. In this study, Zr/Nb multilayers were irradiated with 50 keV He+ ions to a fluence of 1 × 1017 ions/cm2 at temperatures of room temperature, 350 °C, and 500 °C to investigate irradiation-induced structural changes. X-ray diffraction (XRD) analysis indicated low-angle shifts of 0.08-0.54° and high-angle shifts of 0.08-0.42° in the irradiated Zr and Nb layers, suggesting tensile and compressive strains, respectively. At 500 °C, the selected-area electron diffraction (SAED) observed a 9.2% lattice expansion in Zr and a 0.13% contraction in Nb. Geometric phase analysis (GPA) revealed varying strain distributions, transitioning from incoherent to coherent interfaces with increasing irradiation damage. Transmission electron microscopy (TEM) identified the presence of He bubbles in the Zr layer as one of the reasons for strain differences. Nanoindentation tests showed an increase at a depth of 150 nm hardness of 0.831 GPa at 500 °C compared to 350 °C. These results are attributed to differences in crystal structure, vacancy dynamics, interfacial effects, and lattice strain influences. Stability of Zr/Nb interfaces after He irradiation was studied. This study provides insights into the radiation behavior of Zr/Nb nanoscale metallic materials, enhancing our understanding of their potential as structural materials in nuclear energy systems.

Motion Tape Strain During Trunk Muscle Engagement in Young, Healthy Participants

Background: Motion Tape (MT) is a low-profile, disposable, self-adhesive wearable sensor that measures skin strain. Preliminary studies have validated MT for measuring lower back movement. However, further analysis is needed to determine if MT can be used to measure lower back muscle engagement. The purpose of this study was to measure differences in MT strain between conditions in which the lower back muscles were relaxed versus maximally activated. Methods: Ten participants without low back pain were tested. A matrix of six MTs was placed on the lower back, and strain data were captured under a series of conditions. The first condition was a baseline trial, in which participants lay prone and the muscles of the lower back were relaxed. The subsequent trials were maximum voluntary isometric contractions (MVICs), in which participants did not move, but resisted the examiner force in extension or rotational directions to maximally engage their lower back muscles. The mean MT strain was calculated for each condition. A repeated measures ANOVA was conducted to analyze the effects of conditions (baseline, extension, right rotation, and left rotation) and MT position (1–6) on the MT strain. Post hoc analyses were conducted for significant effects from the overall analysis. Results: The results of the ANOVA revealed a significant main effect of condition (p &lt; 0.001) and a significant interaction effect of sensor and condition (p = 0.01). There were significant differences in MT strain between the baseline condition and the extension and rotation MVIC conditions, respectively, for sensors 4, 5, and 6 (p = 0.01–0.04). The largest differences in MT strain were observed between baseline and rotation conditions for sensors 4, 5, and 6. Conclusions: MT can capture maximal lower back muscle engagement while the trunk remains in a stationary position. Lower sensors are better able to capture muscle engagement than upper sensors. Furthermore, MT captured muscle engagement during rotation conditions better than during extension.

Right-sided exercise-induced cardiac remodelling is more pronounced in white than in black elite football players

Abstract Background Most echocardiography studies investigating exercise-induced cardiac remodelling (EICR) in athletes have predominantly focused on left ventricular end-diastolic volume (LVEDV) and wall thickness. Moreover, studies investigating right-sided EICR in individuals with different ethnic backgrounds are scarce, but are needed to assist clinicians in the differentiation between EICR and pathology. Purpose To investigate differences in right-sided EICR between Caucasian (white) and Sub-Saharan (black) male elite football players. Methods We included all male elite football players with echocardiography data from the Evaluation of Lifetime participation in Intensive Top-level sports and Exercise (ELITE) cohort. ELITE collects data from standardised cardiovascular screenings of elite level athletes in the Netherlands, including (but not limited to) standardised resting transthoracic echocardiograms (TTE). Athletes with known cardiovascular disease were excluded. Our primary metrics of interest were right ventricular end-diastolic diameter (RVEDD), maximal dimension of the inferior vena cava (IVC) and right atrial (RA) reservoir, conduit and contractile strain (measured using 2D-Speckle tracking). Secondary metrics of interest included LV ejection fraction (LVEF), LV mass index (LVMi) and left atrial reservoir strain. All metrics of interest were stratified by ethnicity, and indexed for body surface area (BSA) if appropriate. Results A total of 74 elite football players were included (black n = 37; white n = 37), with similar age (18 [2.0] vs 19 [3.0], p = 0.013) and BSA (2 [0.1] vs 2 [0.2] m2, p = 0.268) across ethnicities. There were no differences in indexed LA (35 [10.0] vs 33 [10.0] ml/m2, p = 0.417) and RA volumes (27 [7.4] vs 27 [6.6] ml/m2,p = 0.953). However, black athletes demonstrated smaller max IVC (18 [5.0] vs 25 [5.0] cm, p = &amp;lt;0.001) and RVEDD (40 [2.0] vs 43 [6.0] mm,p = 0.001). Moreover, black athletes demonstrated less RA deformation in the reservoir (31 [8.0] vs 36 [8.0] %, p = 0.003) and contractile phases (9 [4.0] vs 11 [4.0] %, p = 0.017) than white athletes. There were no ethnic-specific differences in RA conduit strain (23 [7.0] vs 25 [6.0] %, p = 0.076). We found no statistically significant differences in LVEF (55 [6.0] vs 55 [6.0] %, p = 0.914), LVMi (92 [15.0] vs 88 [26.8] g/m2, p = 0.236) or LA reservoir strain (32 [7.0] vs 33 [7.0] %, p = 0.157) in black vs white athletes. Conclusion Male elite football players with a Sub-Saharan ethnic background demonstrate less pronounced right-sided EICR than athletes with a Caucasian ethnic background. Our findings emphasize the need for ethnic-specific reference ranges for right-sided EICR to aid in the differentiation between EICR and pathology.

Differences in cardiac magnetic resonance imaging bi-atrial strain between elite athletes and atrial fibrillation patients

Abstract Background Elite athletes frequently demonstrate outspoken bi-atrial dilation, even exceeding volumes seen in patients with atrial fibrillation (AF). Hence, distinguishing atrial exercise-induced adaptation from maladaptation or atrial pathology cannot be done using volumes only. However, data on bi-atrial strain in athletes compared with AF patients investigated using cardiac magnetic resonance imaging (CMR). Methods We performed a retrospective cross-sectional analysis of CMR data comparing three groups: (1) elite athletes included in the ELITE-cohort at the Amsterdam UMC (&amp;gt; 16 years of age and train ≥ 10 hours/week at (inter)national or Olympic level, (2) paroxysmal- (PAF) and persistent AF patients awaiting PVI and (3) healthy controls. All participants underwent CMR in sinus rhythm. Left- and right atrial (LA/RA) reservoir (RES), conduit (CD) and contractile (CT) strain were analysed by automatic feature tracking (FT). Results We included a total of 340 elite athletes (median age 28 years [17, 67]; female n=145 (42.6%)), 103 AF patients (median age 60 [29, 75], female n=36 (35%), PAF n=74 (71.8%), persistent AF n=29 (28.2%), and 85 healthy controls (median age 28 [16, 72], female n=39 (45.9%). Elite athletes had similar indexed maximal left atrial volumes (LAVI) compared to AF patients (49.6 ml/m2 [41.9, 58.3] vs 47.9 ml/m2 [40.5 ml/m2], p = .25), but larger indexed maximal right atrial volumes (RAVI) (59.3 ml/m2 [50.7, 70.7] vs 44.7 ml/m2 [37.0, 55.7], p &amp;lt; .001). Elite athletes had lower LA RES strain (42.8% [36.7. 49.2]) than controls (47.5% [40.6, 54.3], p &amp;lt; .001) but a higher LA RES than AF patients (34.7% [27.4, 41.6], p &amp;lt; .001). Athletes demonstrated higher LA CD/CT ratio (2.2 [1.8, 2.8]) than healthy controls (1.8 [1.4, 2.2], p &amp;lt; .001) and AF patients (1.4 [1.1, 1.9], p &amp;lt; .001) caused by a higher LA CD in athletes (29.2% [24.7, 34.2] compared to healthy controls (29.1% [24.0, 36.2], p &amp;lt; .001) and AF patients (20.1% [16.2, 25.6], p &amp;lt; .001) and a lower LA CT in both athletes (13.0% [22.1, 15.8] and controls (20.1% [16.2, 25.6], compared to healthy controls (17.2% [14.1, 19.9], p &amp;lt; .001). Elite athletes had lower RA RES strain (51.5% [42.8. 63.4]) than controls (57.3% [48.0, 73.5], p = .001) and higher RA RES than AF patients (44.7% [34.1, 55.0], p &amp;lt; .001). AF patients had lower RA CD (28.3% [20.1, 36.8] than elite athletes (35.9% [28.9, 45.5], p &amp;lt; .001) and healthy controls (41.9% [32.4, 51.1], p &amp;lt; .001). Elite athletes had higher RA CD/CT ratio than AF patients (2.5 [1.9, 3.2] vs 1.9 [1.2, 2.4], p &amp;lt; .001). Conclusion Compared with healthy controls and patients with AF, athletes demonstrate unique bi-atrial characteristics. While LAVI is similar in both elite athletes and AF patients, elite athletes demonstrate larger RAVI and a unique strain profile characterized by a higher bi-atrial CD/CT ratio compared with AF patients, but a reduced bi-atrial RES strain relative to healthy controls yet elevated compared to AF patients.Differences in bi-atrial strain

Unveiling a hide side of the athlete's heart: a CMR focus on the left atrium.

Abstract Background cardiac magnetic resonance (CMR) is the gold standard to evaluate cardiac chambers’ dimensions and function, but data on left atrium (LA) dimensions and function among elite athletes are lacking. Objective to describe LA size and function among a cohort of elite athletes and evaluate eventual differences based on sports discipline and gender. Methods We enrolled 120 Olympic athletes with un-remarkable cardiovascular pre-participation screening tests (mean age 25±5 years, 50% males, 25% skill, 25% power, 25% mixed, 25% endurance). All the athletes underwent CMR without contrast administration. LA dimensions, in terms of absolute and indexed area and volume, were computed using 4- and 2-chamber steady state precession cine-sequences. LA ejection fraction (LAEF) and LA coupling index (LACI index, as the ratio between LA and LV end-diastolic volumes) were calculated. Cine-images were also used to analyse atrial deformation with a dedicated offline software to measure LA global longitudinal strain. LA dimensions and function were compared between males and females and athletes of different sports categories based on European classification. Results Among the entire cohort, endurance athletes showed the greatest remodelling in terms of LA and LV dimensions (Table). There were no significant differences in LAEF and LV-EF between athletes of different sport categories (p=0.121 and p=0.679). A trend in increasing LA volumes and decreasing LA strain consistent with a growing cardiovascular demand was observed, but the only statistically significant difference was between skill athletes and all the other groups for LA volumes (p&amp;lt;0.001), while there were no significant differences in LA strain (p=0.170). LACI did not differ between athletes of different sports categories (p=0.170). Female athletes showed higher LAEF and LA strain than males (respectively 55±5 vs 52±6% p=0.012 and 35±7 vs 32±7%, p=0.009) while LACI did not differ based on gender (19±5% for both females and males, p=0.385). Conclusion Among our cohort of Olympics, LA remodelling was observed in all athletes, being less evident in skill group, as for the LV. Thus, the ratio between LA and LV did not differ between sport categories. LAEF and LA strain were not significantly different between athletes of different sports categories although LA strain was slightly lower in endurance. Female athletes showed higher LAEF and LA strain than males, while LACI was not different based on gender.

Inter-Vendor differences in speckle tracking strain - A ten year follow-up on the Strain Standardization Task Force Inter-Vendor Comparison Study

Abstract Background Global longitudinal strain (GLS) derived from two-dimensional speckle-tracking echocardiography is feasible and accurate. Nonetheless, in 2013, the Inter-Vendor Comparison Study showed significant differences of measurement results among vendors. In order to make tracking-based strain imaging a clinically accepted and useful parameter, it is of outmost importance to have interchangeable and accurate measurement results from all vendors. Purpose To investigate if the efforts of the EACVI/ASE/Industry Task Force to Standardize Deformation Imaging have led to a reduction of inter-vendor differences during the past ten years. Methods In an unique setting, in one single room, 372 echocardiographic examinations were performed in sixty-two subjects (50 male, age 56.1 ± 16.98) with a wide range of left ventricular (LV) function (ejection fraction from 30% to 64%) using ultrasound systems from six manufacturers. Each subject was scanned consecutively on all machines by the same assigned experienced sonographer. For each subject two image sets of LV apical views were acquired in order to assess reproducibility in a true test-retest setting. We assessed mean GLS (GLSAV) as average peak systolic global strain from the three apical views on five vendor-specific and five vendor-independent software solutions. We measured endocardial and mid-/full-wall GLS. Since there is no gold standard method to measure GLS, we compared GLSAV of each vendor to the average of the GLS values only from vendors that provide tracking software solutions (SWS) for clinical use. Results For both endocardial (Figure 1) and mid-/full-wall (Figure 2) GLS measurements from clinical SWS were comparable and within a very narrow range (mean GLS of vendors 17.25 ± 0.3% and 15.36 ± 0.3% respectively). The maximum absolute difference between all SWS was 4.1% and 4.9% strain units for endocardial and mid-/full-wall GLS respectively. GLSAV of each software versus the mean of clinical SWS showed significant correlation for most of the companies (r² &amp;gt;0.8, p&amp;lt;0.001). Test-retest variability of GLS measurements expressed as relative mean error was good and lower than for LV ejection fraction (6.3% on average for mean GLS and 7% for LV ejection fraction, p&amp;gt;0.05). Conclusions Our data show a substantial inter-vendor bias in GLS measurements. Nevertheless, in contrast to the situation ten years ago, companies that provide tracking software solutions for clinical use provide now very similar GLS values. In addition, most companies do now allow mid-/full-wall tracking. Our data indicate that the efforts of the strain standardization task force have been fruitful. A continuing effort is needed until all software providers adhere to the task force consensus recommendations.Figure 1Figure 2

Blood pressure in the early 40s impacts left atrial function by speckle-tracking strain two decades later: data from the ACE 1950 Study

Abstract Background With higher age, the left atrial (LA) wall stiffens, giving rise to impaired reservoir function and a compensatory increase in contractile function. The exposure of systemic blood pressures (BP) through life on the left heart chambers may be an explanation, but long-term follow-up studies are lacking. LA phasic function can be quantified by echocardiographic speckle-tracking strain analysis and provide prognostic information in cardiovascular disease. Purpose To explore the impact of BP in the early 40s on LA function assessed by strain two decades later. Methods A total of 3,706 individuals born in 1950 and residing in Akershus County, Norway, were included in the Akershus Cardiac Examination (ACE) 1950 Study. Baseline examinations were conducted between 2012-2015 and included echocardiography. Of those with available echocardiographic LA strain analyses, 2,399 participants had demographic and clinical data available from the Age 40 Program, a cardiovascular health survey performed when the participants were 40 years old. We assessed the impact of BP at age 40 on LA strain two decades later. Differences in LA reservoir (LASr) and contractile strain (LASct) between systolic (&amp;lt;120, 120-140 and &amp;gt;140mmHg) and diastolic (&amp;lt;70, 70-90, and &amp;gt;90mmHg) BP groups were assessed by ANOVA. Linear regression analyses were performed using BPs as continuous variables. Results Mean age of the 2,399 participants was 40.1±0.3 years at the time of the Age 40 program, and 63.9±0.6 years at the time of the ACE 1950 baseline examination. At age 40, 20.8% of participants had BP ≥140/ ≥90mmHg or used antihypertensive medication. Mean LASr was 35.1±9.2%, while mean LASct was 17.7±5.6%. LASr did not differ significantly between groups of systolic or diastolic BP. LASct, however, showed a statistically significant increase from lower to higher groups of both systolic and diastolic BP (Figure). In linear regression analyses, no associations were found between BPs and LASr, but systolic and diastolic BPs were both significantly associated with LASct (Table). The associations between BPs and LASct remained significant after adjustment for sex, BMI, daily smoking, resting heart rate and hypertension at age 40 (Table). Conclusions Higher systolic and diastolic BP in the early forties were associated with increased LA contractile function two decades later, but no significant changes in LA reservoir function were detected. This indicates contractile function as an early marker of subtle LA dysfunction.Figure.Table.

Unsupervised machine learning identifies distinct phenotypes in cardiac complications of pediatric patients treated with anthracyclines

BackgroundAnthracyclines are essential in pediatric cancer treatment, but patients are at risk cancer therapy-related cardiac dysfunction (CTRCD). Standardized definitions by the International Cardio-Oncology Society (IC-OS) aim to enhance precision in risk assessment.ObjectivesCategorize distinct phenotypes among pediatric patients undergoing anthracycline chemotherapy using unsupervised machine learning.MethodsPediatric cancer patients undergoing anthracycline chemotherapy at our institution were retrospectively included. Clinical and echocardiographic data at baseline, along with follow-up data, were collected from patient records. Unsupervised machine learning was performed, involving dimensionality reduction using principal component analysis and K-means clustering to identify different phenotypic clusters. Identified phenogroups were analyzed for associations with CTRCD, defined following contemporary IC-OS definitions, and hypertensive response.ResultsA total of 187 patients (63.1% male, median age 15.5 years [10.4–18.7]) were included and received anthracycline chemotherapy with a median treatment duration of 0.66 years [0.35–1.92]. Median follow-up duration was 2.78 years [1.31–4.21]. Four phenogroups were identified with following distribution: Cluster 0 (32.6%, n = 61), Cluster 1 (13.9%, n = 26), Cluster 2 (24.6%, n = 46), and Cluster 3 (28.9%, n = 54). Cluster 0 showed the highest risk of moderate CTRCD (HR: 3.10 [95% CI: 1.18–8.16], P = 0.022) compared to other clusters. Cluster 3 demonstrated a protective effect against hypertensive response (HR: 0.30 [95% CI: 0.13– 0.67], P = 0.003) after excluding baseline hypertensive patients. Longitudinal assessments revealed differences in global longitudinal strain and systolic blood pressure among phenogroups.ConclusionsUnsupervised machine learning identified distinct phenogroups among pediatric cancer patients undergoing anthracycline chemotherapy, offering potential for personalized risk assessment.

Short-term effects on sacubitril/valsartan therapy on right ventricle work and mechanics in patients with heart failure and reduced ejection fraction

Abstract Introduction In previous studies, sacubitril/valsartan (ARNI) therapy has been shown to have a positive effect on right ventricle (RV) function and on systolic pulmonary artery pressure in addition to improvement of left ventricle (LV) function in patients with heart failure and reduced ejection fraction (HFrEF). Recently, it was shown that a short-term ARNI therapy compared to valsartan-only therapy led to reduced systemic blood pressure and LV mechanical work, contributing to reduced LV myocardial perfusion and oxygen consumption. Purpose This paper aimed to study the effect of short-term ARNI therapy on RV mechanics and work and pulmonary and LV filling pressures compared to valsartan-only therapy in patients with HFrEF. Methods The study was a phase IV, prospective, randomized, double-blind, parallel-group study in patients with NYHA class II–III heart failure and LV ejection fraction (LVEF) &amp;lt;= 35 %. During a 6-week run-in period, all patients received valsartan therapy, which was up-titrated to the highest tolerated dose level (80 mg bid or 160 mg bid) and then randomized to either valsartan or sacubitril/valsartan. Myocardial oxygen consumption, energetic efficiency of cardiac work, and cardiac and systemic hemodynamics were quantified using echocardiography and 11C-acetate PET before and after 6 weeks of therapy (on stable dose) in 55 patients. The analyses were done with ANCOVA adjusting for pre-randomization values. Results The RV myocardial resting perfusion (mean difference of 0.056 (95% CI, 0.02 to 0.109) ml/g/min, p = 0.041) and RV myocardial oxygen consumption (0.005 (0.001 to 0.010) 1/min, p = 0.015) were significantly lower in the ARNI group compared with the valsartan-only group. The left atrial end-diastolic volume indexed to body surface area (geometric mean difference of 1.071 (95% CI, 0 to 1.148) ml/m2, p = 0.048) and the ratio of early mitral inflow velocity to medial mitral annular early diastolic velocity (mean difference of 2.467 (95% CI, 0.096 to 4.838), p = 0.042) were also significantly lower in the ARNI group compared with the control group. There was no difference between the groups in peak systolic right ventricle to right atrial pressure gradient. Still, the tricuspid annular plane systolic excursion was significantly higher in the valsartan-only group compared with the ARNI group (0.221 (0.039 to 0.404) cm, p = 0.018). There was no difference in RV free wall strain, fractional area change or systolic excursion velocity between the treatment arms (p&amp;gt; 0.262). Conclusions In addition to our earlier findings, sacubitril when added to valsartan appears to reduce also right ventricle myocardial perfusion and oxygen consumption. There was also a reduction in left atrial end-diastolic volume and in early mitral inflow to medial mitral annular early diastolic velocity in the sacubitril/valsartan group as compared to the valsartan-only group, which suggest decreased LV filling pressure.

Left atrial strain differences between hypertensive and sarcomeric left ventricular hypertrophy: a sign of sarcomeric auricular myopathy?

Abstract Introduction In clinical practice, left ventricular (LV) hypertrophy is a common finding that can be caused by physiologic or pathologic conditions. An etiologic diagnosis is extremely important because it may change the prognosis and management of the patient and his family. Left atrial (LA) dysfunction is common due to diastolic dysfunction but, in patients with sarcomeric LV hypertrophy, primary cardiomyopathy disease could also be present. Purpose To evaluate if there are differences in LA function between arterial hypertension (HT) and hypertrophic cardiomyopathy (HCM) patients. Methods 73 patients with HCM (according to ESC guidelines criteria) and 82 patients with HT (under treatment with ≥1 hypertensive drug for ≥3 months) and ≥13mm of LV hypertrophy underwent an echocardiography to assess LA function with strain analysis and LV diastolic function. Continuous normally distributed variables were compared with T-student test and categoric variables with square-chi or exact Fisher test if required, accepting as significant a p-value &amp;lt;0.05. Results Globally, HCM patients showed thicker LV walls and larger LA indexed volumes (18.7±4.7 vs. 13.3±0,8 mm and 44.9±20.7 vs. 30.7±8.8 ml/m2, p&amp;lt;0.000 for both). Also, HCM patients presented diastolic dysfunction and atrial fibrillation history in a higher frequency (31 vs. 7.6% and 16.4% vs. 0%, p&amp;lt;0.000 for both). LA strain was significantly lower in HCM patients as compared to the HT group (LA contractile 11.5±5.8 vs. 17.2±4.4, p&amp;lt;0.000; LA conduit 12.2±5.4 vs. 13.3±3.8, p=0.041; and LA reservoir 23.9±8.7 vs. 31.1±5.9, p&amp;lt;0.000). In the subgroup of patients with moderate-severe LV hypertrophy (&amp;lt;17mm) and no significant mitral regurgitation (n=103; HCM=21, HT=82), LA contractile strain remained lower in HCM as compared to HT patients (13.2±4.8% vs. 17.2±4.4%, p&amp;lt;0.000) (figure 1); without differences in diastolic dysfunction, LA volumes, significant mitral regurgitation or atrial fibrillation history. Conclusions Our results show that LA strain is more impaired in HCM patients as compared to HT patients. Specifically, contractile LA strain remained lower even in those patients with moderate-severe LV hypertrophy, despite having similar LV diastolic function, LA indexed volumes, significant mitral regurgitation, or atrial fibrillation history. These findings could be caused by HCM involvement of the LA myocytes. In the context of moderate-severe hypertrophy of unknown origin with non-significant mitral regurgitation, the detection of abnormally reduced LA strain could indicate the presence of an HCM.Figure 1

Characterisation of Neisseria gonorrhoeae strain differences in patients with multisite infection

BackgroundNeisseria gonorrhoeae, the aetiological agent of gonorrhoea, is an increasing global health priority due to high levels of antimicrobial resistance (AMR). It is estimated that up to 42% of patients...

Influence of annealing on microstructures and mechanical properties of laser powder bed fusion and wire arc directed energy deposition additively manufactured 316L

The annealing response of 316L stainless steel manufactured with both laser powder bed fusion (PBF-LB) and wire-arc directed energy deposition (DED-Arc) was investigated in the context of microstructural evolution and mechanical properties. Because additive manufacturing (AM) comprises several technologies that differ in heat source, feedstock, and scan strategy, among other build variables, the final products can experience a range of thermal histories and defect (dislocation) populations. These unique thermal histories can subsequently influence as-built properties and annealing response of AM materials, most notably those manufactured with different AM deposition processes. The PBF-LB process (with higher cooling rates) yielded finer austenite microstructures having more lattice strain, higher dislocation densities, and higher yield strength values than the DED-Arc 316L process (with lower cooling rates). Electron backscattered diffraction (EBSD) data of the kernel average misorientation (KAM), boundary density, and geometrically necessary dislocation (GND) density support the differences in lattice strain. As a result, the PBF-LB 316L exhibited more recovery and recrystallization after annealing at elevated temperatures above 873 K based on changes to yield strength, work hardening behavior, and microstructure evolution. The DED-Arc 316L exhibited a δ-ferrite/austenite microstructure with microsegregation that influenced deformation mechanisms active after annealing. Tensile data, deformed microstructures and misorientation histograms from EBSD showed a decreasing amount of deformation twinning when comparing the as-built condition to annealed conditions (up to 1473 K/1h) of PBF-LB 316L. The opposite trend was noted in DED-Arc 316L. The behavior was interpreted to be due to the differences in chemical segregation during solidification and the effects of heat treatment on chemical homogenization and local stacking fault energy.

Biomimetic Modular Honeycomb with Enhanced Crushing Strength and Flexible Customizability.

The integration of biomimetic principles into the sophisticated design of honeycomb structures has gained significant traction. Inspired by the natural reinforcement mechanisms observed in tree stems, this research introduces localized thickening to the conventional honeycombs, leading to the development of variable-density honeycomb blocks. These blocks are strategically configured to form modular honeycombs. Initially, the methodology for calculating the relative density of the new design is meticulously detailed. Following this, a numerical model based on the plastic limit theorem, verified experimentally, is used to investigate the in-plane deformation models of modular honeycomb under the low- and high-velocity impact and to establish a theoretical framework for compressive strength. The results confirm that the theoretical predictions for crushing strength in the modular honeycomb align closely with numerical findings across both low- and high-velocity impacts. Further investigation into densification strain, energy absorption, and gradient strategy is conducted using both simulation and experimental approaches. The outcomes indicate that the innovative design outperforms conventional honeycombs by significantly enhancing the crushing strength under low-velocity impacts through the judicious arrangement of honeycomb blocks. Additionally, with a negligible difference in densification strains, the modular honeycomb demonstrates superior energy dissipation capabilities compared to its conventional counterparts. At a strain of 0.85, the modular honeycomb's energy absorption capacity improves by 36.68% at 1 m/s and 25.47% at 10 m/s compared to the conventional honeycomb. By meticulously engineering the arrangement of sub-honeycombs, it is possible to develop a modular honeycomb that exhibits a multi-plateau stress response under uniaxial and biaxial compression. These advancements are particularly beneficial to the development of auto crash absorption systems, high-end product transportation packaging, and personalized protective gear.

Dapagliflozin cardiovascular effects on end-stage kidney disease (DARE-ESKD-2) trial: rationale and design.

ABSTRACT Background Dapagliflozin prevents myocardial dysfunction in chronic kidney disease patients regardless residual kidney function, We hypothesized that this effect is extensible also to patients on dialysis. Research design and methods The DARE-ESKD-2 is an ongoing, single-center, open-label randomized clinical trial designed to determine the effects of adding dapagliflozin to standard treatment on myocardial function and structure. Eligible patients were adults on a regular dialysis scheme for more than 3 months. Pregnancy, liver failure, allergy to the investigational drug, and prior use of SGLT2i were exclusion criteria. Participants were randomized in a 1:1 ratio to dapagliflozin or standard treatment groups for 24-weeks. The primary goal is to compare the change in NT-proBNP levels between study arms, and secondary goals include comparing the between-group difference in left ventricle global longitudinal strain, indexed mass, ejection fraction, and E/e` ratio, and on symptoms scale and 6-minute walk test distance. An exploratory analysis will evaluate changes in body composition and bone densitometry. Results The trial has finished the enrollment of 80 patients, that are currently being followed-up. Conclusions This trial will provide novel data on myocardial effects of SGLT2i in dialysis recipients. Results from this study may provide evidence to support SGLT2i use in ESKD.

Oxidation resistance mechanism of copper wire regulated by nano-palladium coating

The microstructure characteristics of palladium coating are the key to the oxidation resistance of palladium-coated copper wire. In this paper, the microstructure characteristics of palladium coating thickness, nanocrystalline size and amorphous band width were controlled by adjusting the process parameters of micro-area coating. The relationship between microstructure characteristics of palladium coating and oxidation resistance was studied. The results show that the wire has good oxidation resistance when the deposition temperature is 400℃ and the copper wire/mold clearances are 2.5 μm. The surface of the copper wire has a palladium coating with a thickness of 74 nm, and the palladium particles are composed of amorphous encapsulated nanocrystals. The relationship between the thickness of palladium coating and the copper wire/mould clearances is y=0.012x+44, and the increase of palladium coating thickness can inhibit the migration of copper ions. The increase in the size of the nanocrystalline and the width of the amorphous band has a certain inhibitory effect on the lattice or grain boundary diffusion of copper to the palladium coating. The multi-stage distorted nanotwins in the amorphous palladium coating can reduce the strain difference at the palladium-copper bonding interface, reduce the diffusion driving force of copper outward, and thus improve the oxidation resistance of palladium-coated copper wires.

Speckle tracking of left ventricle in pediatric patients with hemodynamically significant patent ductus arteriosus (PDA): case–control study

BackgroundLeft ventricle (LV) volume overload is observed with hemodynamically significant PDA as it causes left to right shunting, leading to increased pulmonary blood flow. This overload causes LV remodeling as LV increases stroke volume in trial for compensation, but in larger shunts, patients may develop symptoms of congestive heart failure. Two-dimensional (2D) speckle-tracking echocardiography has emerged as a technique for objective and quantitative evaluation of global and regional myocardial function, independent of the angle of myocardial insonation.Aim of the workThis study aimed to evaluate left ventricular function by 2-dimensional speckle tracking in children with hemodynamically significant PDA.MethodsThis prospective controlled study was performed on 54 children divided into two groups (34 as cases and 20 as controls) to compare echocardiographic measurements. Conventional Echocardiography, tissue Doppler, and Speckle tracking were done for all patients, and measurements were compared.ResultsThere was a statistically significant difference (p value < 0.001) in global longitudinal strain (GLS) in the PDA group indicating a decrease in LV function in PDA patients. This difference was observed in several conventional echocardiographic parameters but not in tissue Doppler in our study.ConclusionLeft ventricle global strain is an important predictor of the myocardial performance index of the Left ventricle in patients with hemodynamically significant PDA and outweighs other conventional echocardiographic parameters and tissue Doppler indices.