Strain Differences Research Articles

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.

The Role of the Lateral Ankle Joint Ligaments on the Stability of the Syndesmosis

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: The tibiofibular syndesmosis is a fibrous joint essential for ankle stability. Injury to the syndesmotic ligaments in high-ankle sprains are destabilizing and cause considerable time lost to injury and long-term disability. Stability imparted by the lateral ankle ligaments in the setting of a high ankle sprain and their interplay has not previously been elucidated in the literature. Sequelae of ligamentous injuries include multidirectional instability and posttraumatic arthritis, likely from altered joint mechanics, impingement, and changes in ligamentous strain. This study aimed to determine the role of individual lateral and syndesmotic ankle ligaments on ankle tissue mechanics and joint stability. We hypothesized that ligament strain and relative bony ankle motion would increase with sequential ligamentous injury. Methods: 22 through-knee lower extremity specimens underwent mechanical testing with an axially loaded external rotation (ER) stress. Specimens were randomized into either a high sprain (sequence 1, n=11, AITFL, IOL, PITFL, ATFL, CFL) or low sprain (n=11, ATFL, CFL, AITFL, IOL, PITFL) ligament transection sequence. Specimens were mounted on an MTS load frame (MTS Inc. Eden Prairie, MN), axially loaded to 750 N, and 5Nm of ER torque stress was applied. Degrees to target ER torque were compared between sequences using linear regression modeling. AITFL and ATFL strain was measured throughout load application using an optical digital image correlation system (ARAMIS, GOM, Braunschweig, Germany). Mean strain was measured for loading tests after each sequential ligament transection. Signed rank tests were utilized to compare the mean strain in the AITFL or ATFL referencing the intact specimen. Results: Upon application of 5 Nm of torque in intact specimens, mean ATFL strain was consistently higher vs AITFL strain. In the high sprain group, ATFL strain gradually decreased after each syndesmotic ligament transection. No statistical differences were identified in this trend vs intact specimens (p=0.69,p=0.44, p=0.69, for AITFL, IOL, PITFL transection). Torsional angle increased with each ligament transection within the high sprain group. In contrast, AITFL strain and torsional angle remained constant after each lateral ligament transection in low ankle sprains. No significant difference in strain on the AITFL in the (p=0.69 and p=0.94) for ATFL and CFL transection, respectively. For both groups, there was no statistically significant difference in rotation angle resulting from 5 Nm of applied ER force after any individual ligament transection. Conclusion: This study used a novel strain tracking approach to quantify the ligament strain in high and low ankle sprains. Contrary to the initial hypothesis, it was found that ATFL strain decreased, and ankle rotation increased with increasing severity of high sprain. AITFL strain and ankle rotation angles remained consistent through increasing severity of low sprains. While the differences in rotation and strain were not statistically significant, greater ankle rotation could amplify the trends identified in ligament strain behavior. It is expected the reduction in strain results from bony impingement under greater rotation in the ligament deficient ankles.

Long Term Follow Up of Biatrial Function after Transcatheter Closure of Atrial Septal Defect

Abstract Aim and Objectives The aim of the study is to evaluate long term right and left atrial function using volumetric analysis and strain indices in patients who underwent transcatheter atrial septal defect (ASD) device closure more than 3 years ago. Patients and Methods This study included a group of 40 patients diagnosed with ASD who came for regular follow up at congenital heart disease clinic and another group of 40 healthy controls (age and sex matched). Basic transthoracic echocardiographic examination was done to both groups followed by assessment of atrial function using modified simpson’s method to measure right and left atrial volumes and 2D speckle tracking technique to assess biatrial strain in the three different phases (reservoir, conduit and contractile strain). Results In our study the results showed that there is no significant difference between the patients group and control group regarding volumetric analysis. Regarding left atrial (LA) strain values, there was no difference in reservoir and conduit strain while contractile strain was significantly lower in the patients group (p- value=0.047). On the other hand, all right atrial (RA) strain values were significantly lower in the patients group than control group (p-value&amp;lt;0.05). A subgroup analysis based on age at closure showed that patients underwent closure at age less than 15 years old had significantly higher strain values for all right and left strain indices compared to those who underwent ASD closure at age of 15 years old or older. Conclusion ASD closure at earlier age is associated with better outcomes regarding atrial function. Long term follow-up in patients who underwent ASD closure more than 3 years ago showed similar LA strain values to control except for lower contractile strain while RA strain values were significantly lower in the patients group. Patients who underwent closure at age less than 15 years old had almost normal right and left strain values while those who underwent closure equal to or more than 15 years old had impaired strain values. Earlier closure is associated with better reverse remodeling and atrial function can turn into normal in patients treated earlier.

CT-derived myocardial strain measurement in patients with chronic constrictive pericarditis

BackgroundWe aimed to compare computed tomography (CT)-derived myocardial strain between patients with constrictive pericarditis (CP) and a matched healthy control group and to identify factors associated with clinical outcomes after pericardiectomy. MethodsThis retrospective study included 65 patients with CP (mean age: 58.9 ​± ​8.0 years) and 65 healthy individuals (mean age: 58.0 ​± ​6.5 years) who underwent multiphase cardiac CT. The type of CP was classified as calcified CP or fibrotic CP. CT-derived strains from four cardiac chambers were compared between the CP and control groups, as well as between different types of CP. Clinical and CT-derived factors associated with adverse outcomes were identified using Cox regression analysis. ResultsCompared with the control group, the CP group showed significantly lower values of left atrium (LA) reservoir strain (15.7 ​% vs. 27.4 ​%), right atrium (RA) reservoir strain (15.1 ​% vs. 27.0 ​%), left ventricle (LV) global longitudinal strain (GLS) (−17.0 ​% vs. −19.5 ​%), and right ventricle free wall longitudinal strain (−21.1 ​% vs. −25.9 ​%) (all p ​< ​0.001). Biatrial reservoir strains and LV GLS were significantly lower in those with calcified CP compared to those with fibrotic CP. LA reservoir strain (hazard ratio, 0.91–95 ​% confidence interval, 0.86–0.96– p ​= ​0.001) was an independent prognostic factor for adverse events in patients with CP. ConclusionCardiac strain differences in CP were predominantly observed in the LA and RA compared to the healthy control group. Biatrial reservoir strains were specifically impaired in those with calcified CP than in those with fibrotic CP. LA reservoir strain was associated with prognosis in patients with CP following pericardiectomy.

Hepatic transcriptomic analysis reveals differential regulation of metabolic and immune pathways in three strains of chickens with distinct growth rates exposed to mixed parasite infections.

During parasite infections, the liver may prioritise immune-related pathways over its metabolic functions. Intestinal infections caused by Ascaridia galli and Heterakis gallinarum impair feed intake, nutrient absorption, and weight gain. Histomonas meleagridis, vectored by H. gallinarum, can also damage liver tissues, potentially impairing liver functions. This study examined the hepatic gene expression in three strains of chickens: Ross-308 (R), Lohmann Brown Plus (LB), and Lohmann Dual (LD), 2weeks after an experimental infection (n = 18) with both A. galli and H. gallinarum or kept as uninfected control (n = 12). Furthermore, H. gallinarum infection led to a co-infection with H. meleagridis. The mixed infections reduced feed intake and the average daily weight gain (P < 0.001). The infections also increased the plasma concentrations of alpha (1)-acid glycoprotein and the antibody titre against H. meleagridis (P = 0.049), with no strain differences (P > 0.05). For host molecular response, 1887 genes were differentially expressed in LD, while 275 and 25 genes were differentially expressed in R and LB, respectively. The up-regulated genes in R and LD were mostly related to inflammatory and adaptive immune responses, while down-regulated genes in LD were involved in metabolic pathways, including gluconeogenesis. Despite performance differences among the strains, worm burdens were similar, but hepatic molecular responses differed significantly. Moreover, there was an indication of a shift in hepatic functions towards immune-related pathways. We, therefore, conclude that the liver shifts its functions from metabolic to immune-related activities in chickens when challenged with mixed parasite species.

Redistribution of SOD3 expression due to R213G polymorphism affects pulmonary interstitial macrophage reprogramming in response to hypoxia.

The extracellular isoform of superoxide dismutase (SOD3) is decreased in patients and animals with pulmonary hypertension (PH). The human R213G single-nucleotide polymorphism (SNP) in SOD3 causes its release from tissue extracellular matrix (ECM) into extracellular fluids, without modulating enzyme activity, increasing cardiovascular disease risk in humans and exacerbating chronic hypoxic PH in mice. Given the importance of interstitial macrophages (IMs) to PH pathogenesis, this study aimed to determine whether R213G SOD3 increases IM accumulation and alters IM reprogramming in response to hypoxia. R213G mice and wild-type (WT) controls were exposed to hypobaric hypoxia for 4 or 14 days compared with normoxia. Flow cytometry demonstrated a transient increase in IMs at day 4 in both strains. Contrary to our hypothesis, the R213G SNP did not augment IM accumulation. To determine strain differences in the IM reprogramming response to hypoxia, we performed RNAsequencing on IMs isolated at each timepoint. We found that IMs from R213G mice exposed to hypoxia activated ECM-related pathways and a combination of alternative macrophage and proinflammatory signaling. Furthermore, when compared with WT responses, IMs from R213G mice lacked metabolic remodeling and demonstrated a blunted anti-inflammatory response between the early (day 4) and later (day 14) timepoints. We confirmed metabolic responses using Agilent Seahorse assays, whereby WT, but not R213G, IMs upregulated glycolysis at day 4 that returned to baseline at day 14. Finally, we identify differential regulation of several redox-sensitive upstream regulators that could be investigated in future studies.NEW & NOTEWORTHY Redistributed expression of SOD3 out of tissue ECM due to the human R213G SNP exacerbates chronic hypoxic PH. Highlighting the importance of macrophage phenotype, our findings reveal that the R213G SNP does not exacerbate pulmonary macrophage accumulation in response to hypoxia but influences their metabolic and phenotypic reprogramming. We demonstrate a deficiency in the metabolic response to hypoxic stress in R213G macrophages, associated with weakened inflammatory resolution and activation of profibrotic pathways implicated in PH.

Mechanism-based shift factors to predict the fatigue performance of cemented pavement materials

Cemented pavement materials (CPMs) are essential components in pavement structures, yet accurately predicting their service life due to fatigue damage remains challenging. Laboratory fatigue test results are commonly employed to predict the service life of CPMs by applying a lab-to-field shift factor (SF). However, traditional approaches rely heavily on experimental data, posing challenges in ensuring the certainty of lab-to-field results. Additionally, inconsistencies in lab-to-field fatigue failure criteria further complicate SF development. To address these challenges, this study proposes a mechanism-based methodology for developing SF. This methodology comprises a rigorous two-scale fatigue model developed by the authors to characterise the fatigue performance of CPMs at the lab scale and predict their performance at the field scale, thereby facilitating the development of SFs. These SFs are established based on a consistent lab-to-field fatigue failure criterion (i.e. the modulus reduction of CPMs). By accounting for strain differences between laboratory and field scales, SFs are derived in the strain-fatigue life space. Application of this approach to typical Australian CPMs, namely siltstone and hornfels, yields mechanism-based SFs of 1.19 and 1.21, respectively.

A robust low-friction triple network hydrogel based on multiple synergistic enhancement mechanisms

Hydrogels exhibit promising applications, particularly due to their high water content and excellent biocompatibility. Despite notable progress in hydrogel technology, the concurrent enhancement of water content, mechanical strength, and low friction poses substantial challenges to practical utilization. In this study, employing molecular and network design guided based on multiple synergistic enhancement mechanisms, we have developed a robust polyvinyl alcohol (PVA)–polyacrylic acid (PAA)–polyacrylamide (PAAm) three-network (TN) hydrogel exhibiting high water content, enhanced strength, low friction, and fatigue resistance. The hydrogel manifests a water content of 63.7%, compression strength of 6.3 MPa, compression modulus of 2.68 MPa, tensile strength reaching 7.3 MPa, and a tensile modulus of 10.27 MPa. Remarkably, even after one million cycles of dynamic loading, the hydrogel exhibits no signs of fatigue failure, with a minimal strain difference of only 1.15%. Furthermore, it boasts a low sliding coefficient of friction (COF) of 0.043 and excellent biocompatibility. This advancement extends the applications of hydrogels in emerging fields within biomedicine and soft bio-devices, including load-bearing artificial tissues, artificial blood vessels, tissue scaffolds, robust hydrogel coatings for medical devices, and joint parts of soft robots.

α-Synuclein Conformations in Plasma Distinguish Parkinson's Disease from Dementia with Lewy Bodies.

Aggregation of misfolded α-synuclein (aSyn) within the brain is the pathologic hallmark of Lewy body diseases (LBD), including Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Evidence exists for aSyn "strains" - conformations with distinct biological properties. However, biomarkers for PD vs. DLB, including potential aSyn strain differences, are lacking. Here, we used two monoclonal antibodies selective for different in vitro aSyn species - termed Strain A and B - to evaluate human brain tissue, cerebrospinal fluid (CSF), and plasma. Surprisingly, levels of Strain A and B aSyn species differed in plasma from individuals with PD vs. DLB in two independent cohorts. Lower plasma aSyn Strain A species also predicted subsequent PD cognitive decline. Strain A and Strain B aSyn species were undetectable in CSF, but plasma aSyn species could template aSyn fibrillization, particularly in PD. Our findings suggest that aSyn strains may impact LBD clinical presentation and originate outside the brain.

Alcohol and fear conditioning produce strain-specific changes in the dorsal hippocampal transcriptome of adolescent C57BL/6J and DBA/2J mice.

Adolescent sensitivity to alcohol is influenced by genetic background. Data from our laboratory suggested that adolescent C57BL/6J and DBA/2J inbred mice differed in susceptibility to alcohol-induced deficits in dorsal hippocampus-dependent contextual fear learning. To investigate the biological underpinnings of this strain difference, we examined dorsal hippocampus gene expression using RNA-sequencing after alcohol or saline administration followed by Pavlovian fear conditioning across male and female C57BL/6J and DBA/2J adolescents. Strains exhibited dramatic differences in dorsal hippocampus gene expression. Specifically, C57BL/6J and DBA/2J strains differed by 3526 transcripts in males and 2675 transcripts in females. We identified pathways likely to be involved in mediating alcohol's effects on learning, including networks associated with Chrna7, a gene encoding the nicotinic cholinergic receptor alpha 7 subunit, and Fmr1, a gene encoding the fragile X messenger ribonucleoprotein. These findings provide insight into the mechanisms underlying strain differences in alcohol's effects on learning and suggest that different biological networks are recruited for learning based on genetics, sex, and alcohol exposure.

Probing the interplay of interactions, screening and strain in monolayer MoS2 via self-intercalation

Controlling many-body interactions in two-dimensional systems remains a formidable task from the perspective of both fundamental physics and application. Here, we explore remarkable electronic structure alterations of MoS2 monolayer islands on graphene on Ir(111) induced by non-invasive self-intercalation. This introduces significant differences in morphology and strain of MoS2 as a result of the modified interaction with the substrate. Consequently, considerable changes of the band gap and non-rigid electronic shifts of valleys are detected, which are a combined effect of the screening of the many-body interactions and strain in MoS2. Furthermore, theory shows that each substrate leaves a unique stamp on the electronic structure of two-dimensional material in terms of those two parameters, restricted by their correlation.

Study on instrumental coupler for heavy haul train

As a crucial load-bearing component, coupler’s safety is pivotal for sustainable railway industry development and is extensively scrutinized due to its complex loading environment. However, current research predominantly concentrates on the longitudinal dynamic behavior of couplers, neglecting factors such as nodding and shaking during traversals along curves and ramps. This study proposes an innovative method aimed at identifying multiple loads on couplers, which includes longitudinal tension and compression, lateral shaking, and vertical nodding forces. A theoretical load identification method based on strain sum and difference on coupler shank faces under various loading scenarios is established by finite element analysis. To facilitate accurate measurement, Wheatstone bridges are employed for three-dimensional force measurement, facilitating strain calculation and temperature compensation. The validity of the proposed approach is confirmed through comprehensive validation, encompassing finite element simulation, laboratory experimentation, and vehicle tests. Results demonstrate the robustness of the method, with maximum load deviations of 2.32% longitudinally, 22.52% horizontally, and 19.86% vertically observed during laboratory tests. Results indicate the proposed method’s accuracy and efficiency in heavy haul train coupler load assessment.

Comparing Mental Strain and Subjective Sensations With and Without a Wearable Chair While Performing Simulated Suturing Tasks.

Introduction Prolonged standing during surgery is a cause of musculoskeletal disorders in surgeons. Wearable chairs have reportedly reduced musculoskeletal strain effectively when used in industry. However, discomfort and instability issues may remain. This study examines whether using a wearable chair for surgical procedures imposes negative effects, such as mental or physical strain on surgeons prior to its clinical implementation. Methods This prospective cross-over study compared mental strain and subjective sensations in simulated suturing tasks with and without using Archelis®, a wearable chair (Archelis Inc, Yokohama, Japan). Six surgeons participated in the study. Mental strain was examined using heart rate variations calculated during tasks. Four subjective sensations (fatigue, comfort, balance, and workability) after each task and differences in body localized pain pre- and post-task were compared using a 10 centimetres (cm)-visual analog scale (VAS) score questionnaire. Results Results showed no significant differences in mental strain nor subjective sensations with or without the wearable chair. The mean VAS scores for all four subjective sensations with the wearable chair were relatively positive. There was a slight yet insignificant post-task increase in VAS mean scores for body-localized pain in the lower legs. Conclusions Significant negative effects on surgeons from the wearable chair were not observed during simulated suturing procedures. This demonstrates no major barriers in the initial phases of wearable chairs integration into the surgery environment.

Real-time acid production and extracellular matrix formation in mature biofilms of three Streptococcus mutans strains with special reference to xylitol

BackgroundAcidogenicity and production of an extracellular matrix (ECM) are important virulence factors for the dental caries-associated bacteria, such as Streptococcus mutans, that live in biofilms on tooth surface. The ECM protects the bacteria from the flushing and buffering effects of saliva resulting in highly acidic microenvironments inside the biofilm. Materials and methodsIn this in vitro study, we applied real-time assays to follow biofilm formation and pH decrease in a growth medium and saliva by three S. mutans strains, as well as acid neutralization inside the mature biofilm. Results were compared with the biofilm composition. Effects of a non-fermentable polyol, xylitol, on acid production and acid neutralization in mature biofilms were evaluated by real-time pH measurements and confocal microscopy. ResultsCombination of real-time pH measurements with biofilm accumulation assays revealed growth media dependent differences in the pH decrease and biofilm accumulation, as well as strain differences in acid production and biofilm formation but not in the buffer diffusion through ECM. The presence of xylitol reduced the pH drop during biofilm formation of all strains. In addition, with strain Ingbritt xylitol reduced the amount of ECM in biofilm, which increased the rate of acid neutralization inside the biofilm after buffer exposure. ConclusionOur results stress the importance of biofilm matrix in creating the acidic environment inside a S. mutans biofilm, especially in the presence of saliva. In addition, our results suggest a novel mechanism of xylitol action. The observed increase in the permeability of the S. mutans ECM after xylitol exposure may allow acid-neutralizing saliva to reach deeper layer of the biofilms and thus, in part, explain previous clinical observations of reduced plaque acidogenicity after frequent xylitol use.

A systematic review and meta-analysis of randomized controlled trials to reduce burden, stress, and strain in informal stroke caregivers

Objectives To understand the nature and effectiveness of interventions aimed at improving informal stroke caregiver burden, stress, and strain. Data sources In line with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic search of CENTRAL, CINAHL, MEDLINE, Embase, APA PsycInfo, and Web of Science was conducted in May 2022. Review methods Studies were eligible if they included an intervention designed for informal stroke caregivers, reported on caregiver burden, strain, or stress, were published in English, and used a randomized controlled trial design. An updated search was conducted in June 2024. The methodological quality of studies was appraised using the Cochrane risk-of-bias tool for randomized trials. The data were pooled, and a meta-analysis was completed for caregiver burden and strain outcomes. Results Nineteen studies met inclusion criteria and were meta-analyzed. Interventions ranged from 4 days to 12 months. Most studies incorporated educational and/or support components. Meta-analyses revealed nonsignificant effects on caregiver burden or strain. Significant between-group differences for caregiver strain and burden were, however, found in seven studies. Conclusion Limited studies, small sample sizes, and conflicting results made definitive conclusions on the most effective intervention characteristics for improving caregiver outcomes difficult. Of the 19 studies, seven found significant between-group differences for caregiver outcomes postintervention, and these tended to incorporate educational components and comprised between seven and nine sessions. Further high-quality research is required to identify optimal format, duration, and frequency for improving caregiver outcomes.

Tailoring Deformation Homogeneity of WE43 Alloy through Strain Rate Sensitivity and Back Pressure during Equal Channel Angular Pressing

Equal channel angular pressing (ECAP) of the magnesium alloys at room temperature owing to their limited workability is challenging. Successful ECAP processing of WE43 magnesium faces two main difficulties, heterogeneous distribution of the strain rate and also tensile strain accommodation on the top surface of the workpiece, leading to catastrophic segmentation of the alloy. In this paper, strain rate sensitivity (SRS) was studied to adopt a proper preprocessing of the material before ECAP processing. The SRS exponents, obtained from compression tests, revealed that solution treatment reduced the SRS of the alloy. To mitigate strain accommodation, an ECAP core-sheath configuration was used to induce back pressure for the sake of deformation homogeneity improvement. A combination of experimental processing and 3D finite element method simulations was applied to the solution-treated WE43 alloy with different core sizes and sheath materials. By finding the optimized core sizes and sheath materials with higher strengths, the differences in microhardness and equivalent plastic strain were reduced. Besides, the adequate magnitude of back pressure and the imposed fully compressive stress prevent fragmentation of the WE43 core during ECAP. After stepwise modifications, the plastic strain inhomogeneity index decreased from 1.340 to 0.671.

European Culex pipiens Populations Carry Different Strains of Wolbachia pipientis.

The mosquito Culex pipiens occurs in two ecotypes differing in their mating and overwintering behavior: pipiens mate in open environments and diapause, and molestus also mate in small spaces and is active throughout the year. Cx. pipiens carry Wolbachia endosymbionts of the wPip strain, but the frequency of infection differs between studied populations. Wolbachia infection affects the host reproductive success through cytoplasmic incompatibility. wPip Wolbachia is divided into five types, wPip I-V. The type of wPip carried varies among Cx. pipiens populations. In northern European locations different wPip types are found in the two ecotypes, whereas in southern locations, they often carry the same type, indicating differences in hybridization between ecotypes. In this study, Cx. pipiens specimens of both ecotypes were collected from Sweden and compared to specimens from Norway, England, Italy, and the Netherlands, as well as Cx. quinquefasciatus from Mali and Thailand. The abundance varied, but all specimens were infected by Wolbachia, while the tested specimens of other mosquito species were often uninfected. The wPip strains were determined through the sequence analysis of Wolbachia genes ank2 and pk1, showing that Cx. pipiens ecotypes in Scandinavia carry different wPip strains. The observed differences in wPip strains indicate that hybridization is not frequent and may contribute to barriers against hybridization of the ecotypes in Sweden and Norway.

Interdependence between myocardial deformation and perfusion in patients with T2DM and HFpEF: a feature-tracking and stress perfusion CMR study

BackgroundPatients with diabetes have an increased risk of developing heart failure with preserved ejection fraction (HFpEF). This study aimed to compare indices of myocardial deformation and perfusion between patients with type 2 diabetes mellitus (T2DM) with and without HFpEF and to investigate the relationship between myocardial strain and perfusion reserve.MethodsThis study included 156 patients with T2DM without obstructive coronary artery disease (CAD) and 50 healthy volunteers who underwent cardiac magnetic resonance (CMR) examination at our center. Patients with T2DM were subdivided into the T2DM–HFpEF (n = 74) and the T2DM–non-HFpEF (n = 82) groups. The parameters of left ventricular (LV) and left atrial (LA) strain as well as stress myocardial perfusion were compared. The correlation between myocardial deformation and perfusion parameters was also assessed. Mediation analyses were used to evaluate the direct and indirect effects of T2DM on LA strain.ResultsPatients with T2DM and HFpEF had reduced LV radial peak systolic strain rate (PSSR), LV circumferential peak diastolic strain rate (PDSR), LA reservoir strain, global myocardial perfusion reserve index (MPRI), and increased LA booster strain compared to patients with T2DM without HFpEF (all P < 0.05). Furthermore, LV longitudinal PSSR, LA reservoir, and LA conduit strain were notably impaired in patients with T2DM without HFpEF compared to controls (all P < 0.05), but LV torsion, LV radial PSSR, and LA booster strain compensated for these alterations (all P < 0.05). Multivariate linear regression analysis demonstrated that LA reservoir and LA booster strain were independently associated with global MPRI (β = 0.259, P < 0.001; β = − 0.326, P < 0.001, respectively). Further, the difference in LA reservoir and LA booster strain between patients with T2DM with and without HFpEF was totally mediated by global MPRI. Global stress PI, LA booster, global rest PI, and global MPRI showed high accuracy in diagnosing HFpEF among patients with T2DM (areas under the curve [AUC]: 0.803, 0.790, 0.740, 0.740, respectively).ConclusionsPatients with T2DM and HFpEF exhibited significant LV systolic and diastolic deformation, decreased LA reservoir strain, severe impairment of myocardial perfusion, and elevated LA booster strain that is a compensatory response in HFpEF. Global MPRI was identified as an independent influencing factor on LA reservoir and LA booster strain. The difference in LA reservoir and LA booster strain between patients with T2DM with and without HFpEF was totally mediated by global MPRI, suggesting a possible mechanistic link between microcirculation impairment and cardiac dysfunction in diabetes. Myocardial perfusion and LA strain may prove valuable for diagnosing and managing HFpEF in the future.