Distinct Stress Research Articles

Origin of Two Distinct Stress Relaxation Regimes in Shear Jammed Dense Suspensions.

Many dense particulate suspensions show a stress induced transformation from a liquidlike state to a solidlike shear jammed (SJ) state. However, the underlying particle-scale dynamics leading to such striking, reversible transition of the bulk remains unknown. Here, we study transient stress relaxation behaviour of SJ states formed by a well-characterized dense suspension under a step strain perturbation. We observe a strongly nonexponential relaxation that develops a sharp discontinuous stress drop at short time for high enough peak-stress values. High resolution boundary imaging and normal stress measurements confirm that such stress discontinuity originates from the localized plastic events, whereas system spanning dilation controls the slower relaxation process. We also find an intriguing correlation between the nature of transient relaxation and the steady-state shear jamming phase diagram obtained from the Wyart-Cates model.

Quasi-static compressive mechanical properties of multilayer micro-lattice biomaterials for skull repair

Current skull repair biomaterials used in clinical surgery face problems such as unmatched mechanical properties and poor biocompatibility. To overcome these problems, the multilayer micro-lattice biomaterials (MB) combining both suitable mechanical properties and biocompatibility are proposed based on skull structural characteristics. The quasi-static compressive mechanical properties of MB are studied experimentally, numerically and theoretically, which are verified by experimental results. The typical deformations, such as distinct shear zone and stress concentration of nodes, are observed. The strength and modulus of the above MB specimens are in the range of 86.72 ± 0.84 to 197.73 ± 0.74 MPa and 2.99 ± 0.13 to 7.56 ± 0.54 GPa, respectively. Simultaneously, the properties of MB with gradient design, including positive, negative and hybrid gradient are investigated by finite element (FE) simulation. The MB with hybrid gradient can better match the structural characteristics of skull. Since the designed MB has out-of-plane compression characteristics comparable to that of skull and suitable biological space for cell growth, it can be implanted into the human body to matched surrounding skull tissue well. The insight of MB combining with design constraints of biomaterials provides a novel method for designing/tuning skull repair biomaterials that might result in the optimized clinical skull surgery effect.

Abstract 3040: The eIF2 kinase GCN2 controls expression of key amino acid transporters and is critical for prostate cancer growth and progression

Abstract The Integrated Stress Response (ISR) is central for adaptation and survival of tumor cells in response to exogenous and endogenous stresses. The ISR features a family of protein kinases that phosphorylate the eukaryotic translation initiation factor eIF2 in response to distinct stresses. While phosphoryation of eIF2 reduces global protein synthesis, there is paradoxical induced translation of select stress adapative gene transcripts, including ATF4, which is central for ISR-directed gene transcription. Therefore, the ISR directs translational and transcriptional control that is critical for cancer adaptation to stress. Recently, eIF2 phosphorylation and ATF4 were suggested to play a role in prostate cancer (PCa) growth and survival; however, the specific function of ISR kinase(s), its mode of activation, and mechanisms by which the ISR facilitate PCa progression are not known.We discovered that the eIF2 kinase GCN2 (EIF2AK4) is activated in a range of PCa cell lines, contributing to enhanced eIF2 phosphorylation and ATF4 expression. Genetic or pharmacological inhibition of GCN2 reduced growth in androgen-sensitive and castration-resistant PCa cell lines in culture and cell line-derived and patient-derived xenograft mouse models in vivo. Induction of GCN2 is accompanied by limitations of select amino acids and accumulation of cognate tRNAs that are reported to be activators of GCN2. A transcriptome analysis of PCa cells treated with a specific small molecular inhibitor of GCN2 indicates that this eIF2 kinase was critical for expression of multiple SLC genes, including amino acid transporters previously implicated in different cancers. We determined that GCN2 inhibition decreases intracellular amino acid levels, and reduced aminoacylation of select tRNAs, accounting for reduced growth in PCa cells. Using CRISPR-based phenotypic screens and genome-wide gene expression analyses of control and GCN2-depleted PCa cells, we confirmed the importance of the transporter genes in PCa fitness. One transporter, SLC3A2 (4F2), is a key SLC gene induced by GCN2 and is essential for PCa proliferation. SLC3A2 has been reported to associate with many SLC7 family transporters, allowing for the localization of these transporters to the plasma membrane for amino acid uptake. Of importance, expression of SLC3A2 partially restored amino acid levels and growth due to loss of GCN2. Our results indicate that select amino acid limitations activate GCN2 in PCa, resulting in the upregulation of key amino acid transporters, including SLC3A2, which provides for nutrient import to facilitate protein synthesis and metabolism required for PCa progression. We conclude that GCN2 and the ISR are promising new therapeutic targets for the treatment of PCa. Citation Format: Ricardo Cordova, Jagannath Misra, Nur P. Damayanti, Parth H. Amin, Kenneth R. Carlson, Angela J. Klunk, Emily T. Mirek, Marcus J. Miller, Tracy G. Anthony, Roberto Pili, Ronald C. Wek, Kirk A. Staschke. The eIF2 kinase GCN2 controls expression of key amino acid transporters and is critical for prostate cancer growth and progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3040.

Multi-omics Analysis of Young Portulaca oleracea L. Plants' Responses to High NaCl Doses Reveals Insights into Pathways and Genes Responsive to Salinity Stress in this Halophyte Species.

The online version contains supplementary material available at 10.1007/s43657-022-00061-2.

Vimentin Tail Segments Are Differentially Exposed at Distinct Cellular Locations and in Response to Stress.

The intermediate filament protein vimentin plays a key role in cell signaling and stress sensing, as well as an integrator of cytoskeletal dynamics. The vimentin monomer consists of a central rod-like domain and intrinsically disordered head and tail domains. Although the organization of vimentin oligomers in filaments is beginning to be understood, the precise disposition of the tail region remains to be elucidated. Here we observed that electrophilic stress-induced condensation shielded vimentin from recognition by antibodies against specific segments of the tail domain. A detailed characterization revealed that vimentin tail segments are differentially exposed at distinct subcellular locations, both in basal and stress conditions. The 411–423 segment appeared accessible in all cell areas, correlating with vimentin abundance. In contrast, the 419–438 segment was more scantily recognized in perinuclear vimentin and lipoxidative stress-induced bundles, and better detected in peripheral filaments, where it appeared to protrude further from the filament core. These differences persisted in mitotic cells. Interestingly, both tail segments showed closer accessibility in calyculin A-treated cells and phosphomimetic mutants of the C-terminal region. Our results lead us to hypothesize the presence of at least two distinct arrangements of vimentin tail in cells: an “extended” conformation (accessible 419–438 segment), preferentially detected in peripheral areas with looser filaments, and a “packed” conformation (shielded 419–438 segment), preferentially detected at the cell center in robust filaments and lipoxidative stress-induced bundles. These different arrangements could be putatively interconverted by posttranslational modifications, contributing to the versatility of vimentin functions and/or interactions.

A high stress profile is associated with severe pain in oncology patients receiving chemotherapy.

Oncology patients receiving chemotherapy can experience both cancer and non-cancer pain. In addition, oncology patients face numerous stressors and their responses are highly variable. Stress and pain are intricately linked. The purpose of this study was to evaluate for differences in pain characteristics and mood disturbance among oncology patients with distinct stress profiles. From a sample of 957 patients with and without pain, latent profile analysis identified three groups of patients with distinct stress profiles (i.e., Stressed, Normative, Resilient). In the subset of 671 patients with pain, receiving chemotherapy for breast, lung, gastrointestinal, or gynecologic cancer, we evaluated for differences among the stress profiles in terms of pain characteristics (e.g., intensity, qualities, interference) and mood disturbance (anxiety, depressive symptoms). Compared to Normative patients (n=333; 49.6%), Stressed patients (n=305; 45.5%) reported higher levels of pain intensity, pain interference, anxiety, and depressive symptoms and more commonly described pain as throbbing, shooting, burning, exhausting, tiring, penetrating, nagging, miserable, and unbearable. Compared to Resilient patients (n=33; 4.9%), Stressed patients reported significantly higher mood-related pain interference scores and more severe anxiety and depressive symptoms. A high stress profile is common (45.5%) and is associated with more severe pain and associated symptoms. Efforts to identify and target this group for interventions may improve patient outcomes.

Individual differences in frontal alpha asymmetry moderate the relationship between acute stress responsivity and state and trait anxiety in adolescents

Stress is a risk factor in the development and maintenance of psychopathology, particularly anxiety. Despite theory suggesting differences in stress responsivity may explain heterogeneity in anxiety, findings remain contradictory. This may be due to failure to account for individuals’ neurobiological states and outdated methodologic analyses which confound conceptually and biologically distinct stress response pathways. In 145 adolescents, this study examined whether individual differences in neural activation underlying motivational states, indexed by resting frontal alpha asymmetry (FAA) before and after the Trier Social Stress Test (TSST), moderate the relationship between stress responsivity (measured by cortisol) and anxiety. Adolescents with rightward FAA activation (indexed by changes in resting FAA pre-to-post TSST) and high trait anxiety showed blunted cortisol reactivities while those with leftward FAA activation and high state anxiety showed prolonged cortisol recoveries. Our work reveals individual differences in vulnerability to psychosocial stressors and is the first study to show that FAA activation moderates the relationships between anxiety and distinct phases of the stress response in adolescents.

Mechanofluorochromic Difluoroboron β-Diketonates Based Polymer Composites: Toward Multi-Stimuli Responsive Mechanical Stress Probes.

Developing mechano-responsive fluorescent polymers that exhibit distinct responses to distinct mechanical stresses requires a careful design of the fluorophore in order to tune its interactions with the polymer. A series of mechanofluorochromic (MFC) polymer composites are prepared by dispersing difluoroboron diketonates complexes with various alkyl side-chain lengths (DFB-alkyl) in linear low-density polyethylene. Observation of the resulting polymer composites under a microscope reveals different aggregate sizes of the three DFB-alkyls, thus confirming the functionalization by alkyl side chains as a powerful approach to control the aggregation process in a polymer. Besides, the three polymer composite samples are shown to be sensitive to both stretching and scratching, thereby consisting in the first reported example of MFC polymer responding to these two distinct mechanical stimuli. To establish a structure-property relationship, the strategy consisted in applying controlled tensile or friction forces while simultaneously monitoring fluorescence changes. Interestingly, the intensity of the MFC response to both stretching and scratching depends on the alkyl chain length and thus on the aggregation properties of the fluorophore. According to a time-resolved fluorescence study, the emission is found to originate from different species following the type of applied stress (tensile or friction force).

Numerical simulation of thermal distribution and residual stress characteristic for laser wobble joining of CFRTP and Ti-6Al-4V alloy

The joining of light alloy and carbon fiber reinforced thermoplastics composite (CFRTP) is recently considered to be an effective way to meet the lightweight requirements of components manufacturing in the aviation field. Furthermore, laser joining technology presents an innovative method for joining CFRTP and light alloy with the advantage of high precision, high efficiency and non-contact. In this paper, a thermo-mechanically coupled model for laser wobble joining of CFRTP and Ti-6Al-4V alloy has been established with the combined heat source, which has not been comprehensively studied in the published research. The typical features of the temperature field and the distribution characteristic of the residual stress are analyzed thoroughly under various parameters, whereas the optimized process parameters are attained in terms of the size of the resin melting zone (RMZ) at the interface as well as the maximum value of residual stress. In addition, a validation experiment was implemented to substantiate the established model. The results indicate that the size of RMZ at the interface enlarges appreciably with higher laser power and lower scanning speed. The distinct residual stress concentration around the weld and the asymmetric residual stress concentration inside the CFRTP can be principally interpreted with the comprehensive effect of non-uniform heat input and fixture constraints during the laser joining process. Moreover, according to the size of RMZ as well as the maximum value of residual stress, the optimum parameters are eventually determined as scanning speed of 0.015 m/s and laser power of 2000 W. The simulated result presents substantial consistency with the verification experimental result, therefore corroborating the validity and accuracy of the established model.

Determinants of RPA megafoci localization to the nuclear periphery in response to replication stress.

Upon replication stress, ssDNA, coated by the ssDNA-binding protein RPA, accumulates and generates a signal to activate the replication stress response. Severe replication stress induced by the loss of minichromosome maintenance helicase subunit Mcm4 in the temperature-sensitive Schizosaccharomyces pombe degron mutant (mcm4-dg) results in the formation of a large RPA focus that is translocated to the nuclear periphery. We show that resection and repair processes and chromatin remodeler Swr1/Ino80 are involved in the large RPA foci formation and its relocalization to nuclear periphery. This concentrated accumulation of RPA increases the recruitment of Cds1 to chromatin and results in an aberrant cell cycle that lacks MBF-mediated G1/S accumulation of Tos4. These findings reveal a distinct replication stress response mediated by localized accumulation of RPA that allows the evasion of cell cycle arrest.

A Potential Link Between Negative Affective Responsivity to Daily Stress and Blood Pressure Reactivity to Acute Stress in College‐Aged Adults

Daily stress, defined as the routine challenges of day‐to‐day living and the unexpected small hassles that disrupt everyday life, is predictive of future cardiovascular disease (CVD)‐related health outcomes; however, the underlying mechanisms remain unclear. Given that heightened blood pressure (BP) reactivity to stress is also purported to increase future CVD risk, we examined a potential link between daily stress and acute stress‐induced increases in BP. We hypothesized that increased frequency of daily stressor exposures and greater negative emotional responsiveness to daily stress (i.e., negative affective responsivity) would be positively related to increased BP reactivity to acute stressors in the laboratory setting. Thirty adults (23±5 yrs; 21 female) completed the Daily Inventory of Stressful Events (DISE) interview every day for 8 consecutive days to quantify objective (e.g., frequency) and subjective appraisal characteristics (e.g., emotions) of naturally occurring daily stressors (e.g., stressful event at home/work). On DISE Day 8, mean arterial pressure (MAP; finger photoplethysmography) was measured during two distinct laboratory‐based acute stress stimuli: the cold pressor test (CPT; generalized sympathoexcitatory stimulus) and the Stroop Color Word Test (SCWT; cognitive stress stimulus). Daily stress exposure was calculated as the total number of stressors across the 8‐day protocol, and negative affective responsivity was calculated as the magnitude of the increase in negative affect on stressor exposure days (at least 1 stressor reported) compared to negative affect on non‐stressor exposure days (no stressors reported). BP reactivity was quantified as the peak acute stress‐induced increase in MAP to the CPT and SCWT. Participants experienced a total of 3±3 stressors (range: 0‐9) over the 8‐day interview timeframe. Negative affect was greater on stressor exposure days (0.68±0.50 a.u.) compared to non‐exposure days (0.37±0.36 a.u.; p<0.01). Both the CPT (∆21±7 mmHg) and the SCWT (∆9±6 mmHg) elicited increases in MAP (both p<0.05). The total number of stressors was not related to the peak increase in MAP during either the CPT (slope=‐0.10; r=0.04; p=0.85) or the SCWT (slope=‐0.43; r=19; p=0.31). Negative affective responsivity was positively related to the peak increase in MAP during the CPT (slope=12.41; r=0.45; p=0.03) but not the SCWT (slope=3.00; r=0.14, p=0.50). These preliminary data demonstrate that daily stressor exposure by itself is not related to BP reactivity to laboratory stressors in college‐aged adults. However, greater negative affective responsivity is associated with greater acute stress‐induced increases in BP during the CPT, but not the SCWT, perhaps suggesting that the link between daily stress processes and BP reactivity may be dependent on the stress‐responsive neurocircuitry being activated.

Diagnostic and prognostic value of urine biomarkers among women with dysfunctional voiding

The current study aimed to investigate the diagnostic and prognostic value of urine biomarkers among female patients with dysfunctional voiding (DV). Urine samples were collected from 43 female patients with DV and 25 controls. Oxidative stress biomarkers (8-hydroxy-2-deoxyguanosine [8-OHdG], 8-isoprostane, and total antioxidant capacity [TAC]) and inflammatory markers (interleukin-1 beta [IL-1β], IL-2, IL-6, IL-8, tumor necrosis factor alpha, nerve growth factor, and brain-derived neurotrophic factor) levels were analyzed. In total, 26 patients with DV received further treatment with biofeedback pelvic floor muscle exercise or external urethral sphincter botulinum toxin A injections. Patients with DV had significantly higher urine 8-OHdG, IL-1β, IL-8, and brain-derived neurotrophic factor levels than controls. Both urine 8-OHdG and IL-1β levels were positively correlated with clinical symptoms. Patients with DV who had successful treatment outcomes had significantly lower pretreatment urine 8-isoprostane and TAC levels than those with unsuccessful outcomes. The pretreatment urine TAC level was the only independent predictor of successful treatment outcomes (odds ratio: 0.995). Compared with controls, female patients with DV had distinct urine oxidative stress biomarker and inflammatory marker profiles, which also mapped their clinical characteristics and treatment outcomes. These urine analytes might have diagnostic and prognostic values among female patients with DV.

Effect of coating architecture on stress and energy relief efficiency of TiZrN coating on Si substrate

This study aims to investigate the extent of stress relief achieved by employing different types of coating architectures, and evaluate the energy relief efficiency in the coating architectures by an energy-balance physical model. TiZrN, TiZrN/Ti, TiZrN/TiN and TiZrN/TiN/Ti coatings with various thickness of TiN were deposited by unbalanced magnetron sputtering. Laser curvature method and the average X-ray strain method combined with nanoindentation were used to measure the residual stress of the entire coating and individual layers, respectively. Experimental results showed that higher stress relief in TiZrN coating could be attained by introducing an interlayer with TiN/Ti architecture than by adding a single Ti interlayer. The tri-layer specimen with a 300-nm TiN layer showed the largest stress relief among all specimens, where the TiZrN coating had the lowest residual stress, -2.01 GPa. The energy-balance model postulated that the release of stored elastic energy in the top coating and in the Si substrate were both converted into the plastic work of the Ti interlayer. The model analysis indicated that the TiN transitional layer served as a channel that effectively transferred the stored elastic energy in TiZrN to the Ti interlayer, by which the distinct stress gradient at the original TiZrN/Ti interface could be reduced, thereby increasing the plastic deformation capacity of the underlying Ti interlayer, and therefore a larger fraction of the residual stress in TiZrN was relieved compared to the TiZrN/Ti bilayer coating. Adding a TiN transitional layer into the TiZrN/Ti coating system only slightly changed the overall energy relief efficiency, while it increased the energy relief fraction in the TiZrN coating. The stress relief in an architectured coating, including transitional layer and metal interlayer, should be evaluated based on the measurements of overall stress and the stress in the major hard coating. The energy balance model could be employed to differentiate the fraction of energy relief in hard coating and in Si substrate, by which the efficiency of stress relief, or energy relief, could be correctly revealed.

Distinct Stress-Dependent Signatures of Cellular and Extracellular tRNA-Derived Small RNAs.

The cellular response to stress is an important determinant of disease pathogenesis. Uncovering the molecular fingerprints of distinct stress responses may identify novel biomarkers and key signaling pathways for different diseases. Emerging evidence shows that transfer RNA‐derived small RNAs (tDRs) play pivotal roles in stress responses. However, RNA modifications present on tDRs are barriers to accurately quantifying tDRs using traditional small RNA sequencing. Here, AlkB‐facilitated methylation sequencing is used to generate a comprehensive landscape of cellular and extracellular tDR abundances in various cell types during different stress responses. Extracellular tDRs are found to have distinct fragmentation signatures from intracellular tDRs and these tDR signatures are better indicators of different stress responses than miRNAs. These distinct extracellular tDR fragmentation patterns and signatures are also observed in plasma from patients on cardiopulmonary bypass. It is additionally demonstrated that angiogenin and RNASE1 are themselves regulated by stressors and contribute to the stress‐modulated abundance of sub‐populations of cellular and extracellular tDRs. Finally, a sub‐population of extracellular tDRs is identified for which AGO2 appears to be required for their expression. Together, these findings provide a detailed profile of stress‐responsive tDRs and provide insight about tDR biogenesis and stability in response to cellular stressors.

Structural plasticity in leaves of Schinus terebinthifolius (Anacardiaceae) populations from three contrasting tropical ecosystems1

Schinus terebinthifolius Raddi (Anacardiaceae) is a pioneer tropical species that has been largely used in Brazil for land restoration. The species occurrence encompasses inland ecosystems such as the neotropical savanna (cerrado sensu stricto; Cerrado domain) through coastal ecosystems such as mangroves and the restinga (Atlantic Forest domain), all of which are characterized by environmental factors that highly contrast with one another. We analyzed the leaf anatomy of S. terebinthifolius populations from those three ecosystems aiming to verify whether any particular trait would provide the species with foliar anatomical plasticity, thereby enabling it to adapt to such environmentally disparate areas. We found that thickness of the leaf blade, adaxial palisade parenchyma, and spongy parenchyma differed significantly among the three ecosystems. The population from the restinga, an open, coastal ecosystem subjected to high light incidence, showed the highest means for these variables, followed by the populations from mangrove and cerrado. Leaf blade thickness in the restinga population was higher due mainly to increased palisade parenchyma thickness. The adaxial palisade parenchyma thickness in mangrove individuals was more than double the one in the cerrado population. The abaxial palisade parenchyma thickness showed no difference between the mangrove and restinga populations, yet in those two it was higher than in the cerrado population. Schinus terebinthifolius was revealed to have high potential of acclimating to different ecosystems, owing to a high capacity of developing anatomical responses to distinct stress conditions imposed by the surrounding environment, which confirms the species high phenotypic plasticity. Such high capacity of acclimating to contrasting environmental conditions by means of modulating the thickness of different leaf tissues could provide the species with an adaptive advantage in a climate-change scenario.

Pre‐incubation conditions determine the fermentation pattern and microbial community structure in fermenters at mild hydrostatic pressure

Fermentation at elevated hydrostatic pressure is a novel strategy targeting product selectivity. However, the role of inoculum history and cross‐resistance, that is, acquired tolerance from incubation under distinctive environmental stress, remains unclear in high‐pressure operation. In our here presented work, we studied fermentation and microbial community responses of halotolerant marine sediment inoculum (MSI) and anaerobic digester inoculum (ADI), pre‐incubated in serum bottles at different temperatures and subsequently exposed to mild hydrostatic pressure (MHP; < 10 MPa) in stainless steel reactors. Results showed that MHP effects on microbial growth, activity, and community structure were strongly temperature‐dependent. At moderate temperature (20°C), biomass yield and fermentation were not limited by MHP; suggesting a cross‐resistance effect from incubation temperature and halotolerance. Low temperatures (10°C) and MHP imposed kinetic and bioenergetic limitations, constraining growth and product formation. Fermentation remained favorable in MSI at 28°C and ADI at 37°C, despite reduced biomass yield resulting from maintenance and decay proportionally increasing with temperature. Microbial community structure was modified by temperature during the enrichment, and slight differences observed after MHP‐exposure did not compromise functionality. Results showed that the relation incubation temperature—halotolerance proved to be a modifier of microbial responses to MHP and could be potentially exploited in fermentations to modulate product/biomass ratio.

The Pleiotropic Effects of Oxygen-Derived Free-Radical Scavengers on the Graft During Normothermic Ex Situ Heart Perfusion

<h3>Purpose</h3> The management of oxidative stress is pivotal during ESHP. The lack of sufficient antioxidant systems allow the accumulation of reactive oxygen species (ROS) which can negatively affect myocardial function. We aim to evaluate the use of oxygen-derived free-radical (OFR) scavengers on cardiac functional preservation during ESHP. <h3>Methods</h3> Using a porcine heart perfusion model, we compared the effect of different OFR scavengers. Hearts from juvenile Yorkshire pigs were perfused in working mode for 6 hours either in the control group (n=6) or adding polyethylene glycol (PEG)-catalase (10,000U/L, n=6) and PEG-superoxide dismutase (SOD) (550U/L, n=6) at the initiation of perfusion. Another group (n=6) of freshly procured heart were obtained as tissue control. Contractile function, myocardial injury and endothelial integrity were evaluated. The oxidative modification and antioxidant activity were determined in the myocardium and coronary vasculature. <h3>Results</h3> Cardiac function was better preserved in the catalase group (p<0.05, Figure A). Catalase and SOD both decreased perfusate cTnI, indicating less myocardial injury. The catalase group had lower perfusate vWF than the other two groups, suggesting less endothelial injury (p<0.05, Figure B). Compared to SOD, catalase reduced ROS production and oxidatively modified protein, indicated by protein carbonyl content in the myocardium and nitrotyrosine in the coronary vasculature (p<0.05, Figure C). The catalase and glutathione peroxidase activity decreased in all groups. However, adding catalase partially restored enzyme activity (Figure D). <h3>Conclusion</h3> The antioxidant enzyme activity decreased during <i>ex situ</i> heart perfusion. Catalase better preserved cardiac function and coronary endothelium than SOD, likely resulting from distinct oxidative stress states in the graft. Catalase and SOD have opposing effects on hydrogen peroxide detoxification, which may explain the differences observed in this study.

Enhanced nitrate reductase activity offers Arabidopsis ecotype Landsberg erecta better salt stress resistance than Col-0.

The nitrogen utilization efficiency of plants varies depending on the plant species. In modern agriculture, nitrogen fertilizer is used to increase crop production, with the amount of fertilizer addition increasing steadily worldwide. This study included the two most used ecotypes of Arabidopsis thaliana, Landsberg erecta (Ler) and Col-0, which were used to identify differences at the molecular level. We found that the efficiency of nitrogen utilization and salt stress resistance differed between these two ecotypes of the same species. We demonstrated distinct salt stress resistance between Ler and Col-0 depending on the differences in nitrate level, which was explained by different regulation of the NIA2 gene expression in these two ecotypes. Our results demonstrate that the genes and promoters regulate expression of these genes and contribute to trait differences. Further studies are required on genes and promoter elements for an improved understanding of the salinity stress resistance mechanism in plants.

Profiles of Stress and Coping Associated With Mental, Behavioral, and Internet Use Problems Among Adolescents During the COVID-19 Pandemic: A Stratified Random Sampling and Cluster Analysis.

BackgroundAdolescents are vulnerable to behavioral and mental health problems, which might be further exacerbated during the COVID-19 pandemic. This study explored how participants with different profiles of stressful life events, coping resources (i.e., self-esteem and perceived social support) and coping strategies (i.e., maladaptive and adaptive coping) varied in the prevalence of mental, behavioral, and Internet use problems.MethodsData were collected from a large and representative sample of Chinese secondary school students in Hong Kong (n = 3,136) from September to November 2020 (48.1% males; mean age = 13.6 years old). Cluster analysis and logistic regression models were used for analysis.ResultsThe prevalence of suicidal ideation and sleep disturbance was 29.8 and 55.4%, respectively. Behavioral problems were most frequently reported in excessive social media use (53.5%), followed by excessive Internet gaming (43.6%), obesity (34.1%), damaging properties (14.6%), and alcohol or substance abuse (5.1%). The results of cluster analysis yielded three distinctive stress and coping profiles: severe profile (High Risk/Low Protective; 17.0%), moderate profile (Moderate Risk/Moderate Protective; 35.8%), and mild profile (Low Risk/High Protective; 47.2%). Participants with severe and moderate profiles displayed significantly higher levels of mental (range for AOR: 2.08–15.06; all p < 0.001) and behavioral health problems (range for AOR: 1.22–11.22; all p < 0.05) compared to the mild profile cluster.ConclusionsAdolescents' mental and behavioral health may be shaped by a combination of stressful life events and variations in coping resources as well as strategies. Transdiagnostic and multimodal interventions on these factors are warranted to reduce mental, behavioral, and Internet use problems among adolescents.

Flexural Creep Behaviour of Pultruded GFRP Composites Cross-Arm: A Comparative Study on the Effects of Stacking Sequence.

Pultruded glass fibre reinforced polymer (pGFRP) composites provide outstanding properties for composite polymer cross arms in power transmission line applications. This study has investigated the effects of various stacking sequences of fibres directions of pGFRP on flexural strength and creep behaviour. The use of static four-point bending flexural tests revealed that Stacking Sequence 2 (±45/0/90/0/90/0) had a significant flexural strength of 399.9 MPa while Stacking Sequence 1 (±45/90/0/±45) had a flexural strength of 242.5 MPa. Furthermore, the four-point bending creep experiments were performed at three distinct stress levels, notably 12%, 24%, and 37% of the ultimate flexural strength, to characterise the creep behaviour of distinct stacking sequences. Moreover, Findley’s power law equation for bending creep behaviour has revealed that the time-dependent reduction factor of Stacking Sequence 1 and Stacking Sequence 2 estimates a drop in flexural modulus of 23% and 10% respectively.