Acute kidney injury and cardiogenic shock severity for mortality risk stratification in patients supported with VA ECMO.

AIMS: To assess the stage of acute kidney injury (AKI), as an index of organ perfusion, combined with shock severity, measured by the Society for Cardiovascular Angiography and Interventions (SCAI) shock stage classification, to stratify the risk of mortality in patients diagnosed with cardiogenic shock (CS) and supported with venoarterial extracorporeal membrane oxygenation (VA ECMO). METHODS ANS RESULTS: From January 2018 to December 2020, consecutive adult patients diagnosed with CS and received VA ECMO were retrospectively evaluated. The highest AKI stage within 48 h after ECMO initiation was assessed using the Kidney Disease: Improving Global Outcomes criteria. We included 216 patients with a mean age of 58.8 years and 31.0% were females. 88.4% of patients received ECMO for postcardiotomy, while 11.6% for medical CS. The total in-hospital mortality was 53.2%. AKI occurred in 182 (84.3%) patients receiving ECMO for CS. AKI stage 0, 1, 2, and 3 were present in 15.7%, 17.6%, 18.1%, and 48.6% of patients with in-hospital mortality of 26.5%, 26.3%, 61.5%, and 68.6%, respectively (P < 0.001). The AKI stage (P < 0.001), SCAI shock stage before ECMO (P = 0.008), and NYHA ≥ Class III on admission (P = 0.044) were independent predictors of in-hospital mortality. The area under the receiver operating characteristic curve of 0.754 (95% confidence interval: 0.690 to 0.811) for AKI stage combined with SCAI shock stage was better than those for AKI stage (0.676), SCAI shock stage (0.657), serum lactate level (0.682), SOFA score (0.644), SVAE score (0.582), and VIS score (0.530) prior to ECMO. CONCLUSIONS: In this single-center CS population who received VA ECMO for circulatory support, predominantly postcardiotomy cases, AKI occurred in 84.3% of the patients. AKI stage, as an index of organ perfusion combined with shock severity measured by the SCAI shock classification, demonstrates a good correlation with in-hospital mortality.

A gelatin methacryloyl (GelMA) treated with gallic acid and coated with specially designed nanoparticles derived from ginseng enhances the healing of wounds in diabetic rats.

Due to persistent inflammation and oxidative stress reactions, achieving drug absorption in diabetic wounds is challenging. To overcome this problem, our article presents a composite hydrogel, GelMA-GA/DMOG@GDNP, which consists of gelatin methacryloyl (GelMA) treated with gallic acid (GA) and encapsulating ginseng-derived nanoparticles (GDNPs) loaded with dimethyloxallyl glycine (DMOG). The composite hydrogel demonstrates excellent biocompatibility. In laboratory settings, the hydrogel inhibits the production of nitric oxide synthase 2 (iNOS) in mouse immune cells (RAW264.7 cells), enhances the growth and migration of mouse connective tissue cells (L929 cells) and human endothelial cells (HUVECs), and promotes tube formation in HUVECs. In a rat model of type 1 diabetes-induced wounds, the composite hydrogel attenuates inflammatory reactions, facilitates the formation of fibres and blood vessels, accelerates wound healing, and elucidates specific pathway mechanisms through transcriptome sequencing. Therefore, the GelMA-GA/DMOG@GDNP hydrogel can serve as a safe and efficient wound dressing to regulate the inflammatory response, promote collagen fiber and blood vessel formation, and accelerate wound healing. These findings suggest that utilizing this multifunctional engineered nanoparticle-loaded hydrogel in a clinical setting may be a promising strategy for diabetic wound healing.

The association of triglyceride-glucose index with major adverse cardiovascular and cerebrovascular events after acute myocardial infarction: a meta-analysis of cohort studies.

BACKGROUND: Insulin resistance (IR) is indicated to be linked with adverse outcomes of acute myocardial infarction (AMI), for its pro-inflammatory and pro-thromboplastic function. The triglyceride-glucose (TyG) index is a newly developed substitute marker for IR. The aim of this pooled analysis was to provide a summary of the relationship of TyG index with occurrences of major adverse cardiovascular and cerebrovascular events (MACCEs) among populations suffering from AMI. METHODS: Cohorts reporting multivariate-adjusted hazard ratios of TyG index with MACCEs or its independent events were identified through systematically searching PubMed, MEDLINE, Web of science, Embase and Cochrane databases. Results were combined using a random-effects model. RESULTS: 21 cohorts comprising 20403 individuals were included. Compared to individuals in the lowest TyG category, patients in the highest TyG category exhibited elevated risks of both MACCEs (P < 0.00001) and all-cause death (P < 0.00001). These findings were in line with the results as TyG analyzed as continuous variables (MACCEs: P = 0.006; all-cause death: P < 0.00001). Subgroup analysis demonstrated that diabetic status, type of AMI, nor the reperfusion therapy did not destruct this correlation (for subgroups, all P < 0.05). CONCLUSION: All these indicated that higher TyG index could potentially predict MACCEs and all-cause death in patients with AMI as an independent indicator.

Prognostic implication of Vasoactive Inotropic Score in adult patients with cardiogenic shock on veno-arterial extracorporeal membrane oxygenation.

Background: Vasopressors and inotropes are crucial in managing cardiogenic shock (CS) as they enhance microcirculation in patients. Numerous studies have demonstrated the adverse outcomes associated with excessive use of vasoactive drugs and the vasoactive drug scoring system has emerged as a valuable prognostic tool, particularly in pediatric patients. This study aimed to examine the prognostic significance of the Vasoactive Inotropic Score (VIS) in adult patients with CS receiving veno-arterial extracorporeal membrane oxygenation (VA-ECMO) treatment. Methods: This retrospective multi-center study involved 2,453 adult patients who underwent VA-ECMO in China between 2015 and 2021. Among them, 1,742 adult patients with CS following VA-ECMO were finally included. The maximum VIS (VISmax) was determined by considering the highest doses of vasoactive and inotropic drugs administered within the first 6 hours before ECMO initiation. Based on the VISmax, patients were classified into two groups: 0-20 and >20. The primary outcome of this study was in-hospital mortality. Results: A total of 1,146 patients were included in the high VISmax group, while 596 patients were assigned to the low VISmax group. Overall, 882 (50.6%) patients experienced in-hospital mortality, with significantly higher rates observed among those with higher VISmax scores (41.4% for VIS ≤20 versus 68.3% for VIS >20; P<0.001). Similar trends were observed for 30-day mortality (40.7% for VIS ≤20 versus 64.9% for VIS >20; P<0.001). Multivariable regression analysis demonstrated that a VIS score exceeding 20 independently predicted in-hospital mortality [odds ratio (OR) 2.64; 95% confidence interval (CI): 2.10-3.33; P<0.001]. The receiver operating characteristic (ROC) analysis revealed that VIS had an area under the curve (AUC) of 0.65 (95% CI: 0.63-0.68; P<0.001) as a predictor of in-hospital mortality, with an optimal cutoff value of 20.1. Moreover, the VIS exhibited good predictive ability for in-hospital mortality in patients with acute myocarditis (AUC 0.70; 95% CI: 0.63-0.78; P<0.001). Conclusions: Firstly, higher maximum level of VIS within the first 6 hours before ECMO initiation independently predicted poorer clinical outcomes in patients supported with ECMO for CS. Secondly, VIS exceeding 20 was significantly associated with increased risks of in-hospital mortality and 30-day mortality. Thirdly, when categorized by the cause of CS, a high VIS exhibited good predictive ability in patients with acute myocardial infarction, heart failure, and acute myocarditis.

Addressing the long-standing limitations of double exponential and non-rectangular hyperbolic models in quantifying light-response of electron transport rates in different photosynthetic organisms under various conditions.

The models used to describe the light response of electron transport rate in photosynthesis play a crucial role in determining two key parameters i.e., the maximum electron transport rate (J max) and the saturation light intensity (I sat). However, not all models accurately fit J-I curves, and determine the values of J max and I sat. Here, three models, namely the double exponential (DE) model, the non-rectangular hyperbolic (NRH) model, and a mechanistic model developed by one of the coauthors (Z-P Ye) and his coworkers (referred to as the mechanistic model), were compared in terms of their ability to fit J-I curves and estimate J max and I sat. Here, we apply these three models to a series of previously collected Chl a fluorescence data from seven photosynthetic organisms, grown under different conditions. Our results show that the mechanistic model performed well in describing the J-I curves, regardless of whether photoinhibition/dynamic down-regulation of photosystem II (PSII) occurs. Moreover, both J max and I sat estimated by this model are in very good agreement with the measured data. On the contrary, although the DE model simulates quite well the J-I curve for the species studied, it significantly overestimates both the J max of Amaranthus hypochondriacus and the I sat of Microcystis aeruginosa grown under NH4 +-N supply. More importantly, the light intensity required to achieve the potential maximum of J (J s) estimated by this model exceeds the unexpected high value of 105 µmol photons m-2 s-1 for Triticum aestivum and A. hypochondriacus. The NRH model fails to characterize the J-I curves with dynamic down-regulation/photoinhibition for Abies alba, Oryza sativa and M. aeruginosa. In addition, this model also significantly overestimates the values of J max for T. aestivum at 21% O2 and A. hypochondriacus grown under normal condition, and significantly underestimates the values of J max for M. aeruginosa grown under NO3 -N supply. Our study provides evidence that the 'mechanistic model' is much more suitable than both the DE and NRH models in fitting the J-I curves and in estimating the photosynthetic parameters. This is a powerful tool for studying light harvesting properties and the dynamic down-regulation of PSII/photoinhibition.

Screening of miRNA biomarkers in serum exosomes of patients with thyroid nodules at different iodine levels / 临床检验杂志

Objective To comapre and analyze the differences and commonalities of expression profiles of serum exosomal microRNA between patients with thyroid nodules and healthy persons at different iodine levels,and then provide evidence for screening early diag-nostic markers of thyroid nodules at different iodine levels.Methods The peripheral blood samples from 10 patients with thyroid nod-ules and healthy volunteers at different iodine levels were collected.Their serum iodine levels were measured by the arsenic cerium cat-alytic spectrophotometry.Serum exosomal microRNA were extracted and the expression levels of microRNA were determined by the high-throughput sequencing technology.The differential target genes were predicted and further performed Gene ontology(GO)analysis and Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis.Results Compared with healthy volunteers,there were 6 downreg-ulated miRNAs in the patients with thyroid nodules at different iodine levels,namely miR-324-5p,miR-6511b-3p,miR-9903,miR-550a-3p,miR-5001-3p,and miR-3688-3p.Differentially expressed exosomal microRNA could regulate the MAPK signaling path-way,PI3K-AKT signaling pathway,VEGF signaling pathway,and NF-κB signaling pathway.Conclusion Six differentially expressed microRNAs is identified,which may serve as biological markers for the early diagnosis of thyroid nodules at different iodine levels.

Mechanism of negative pressure wound therapy in the auxiliary treatment of bone and soft tissue infection / 中国组织工程研究

BACKGROUND:As the population ages at an accelerated rate in China,the incidence of bone and soft tissue infections is likewise on the rise.Bone and soft tissue infections can involve all bone and surrounding soft tissues,including the periosteum,cortex,cancellous bone and bone marrow.Examples of such infections include diabetes foot,osteomyelitis,surgical incision infection,and infection around joint prostheses.Owing to the intricate pathogenesis and challenging treatment,it has become increasingly noteworthy in clinical settings.Negative pressure wound therapy is a modern wound treatment which has been gaining popularity,especially in the area of bone and soft tissue infection. OBJECTIVE:To analyze the global research progress in the utilization of negative pressure wound therapy for treating bone and soft tissue infection in recent years. METHODS:Relevant articles in Chinese and English published in PubMed,Web of Science,and CNKI from 1990 to 2022 were retrieved.Search terms were"negative pressure wound therapy,vacuum assisted closure,negative pressure,osteomyelitis,bone infection"in English and Chinese,separately.A total of 711 articles were initially retrieved,out of which 65 articles were included for further review. RESULTS AND CONCLUSION:Negative pressure wound therapy,as an auxiliary approach to treating wounds,has a range of positive effects such as stabilizing wounds,diminishing edema,decreasing bacterial load,encouraging granulation tissue and angiogenesis,enhancing tissue perfusion,modulating peripheral nerves,modulating biological immunity and promoting the growth and differentiation of osteoblasts.This is a more effective method for managing complex wounds,such as bone and soft tissue infections,than traditional dressings with one-dimensional benefits.Numerous studies,both basic and clinical,have demonstrated the safety and efficacy of negative pressure wound therapy in the auxiliary treatment of bone and soft tissue infections.

Dimeric N-Acetyldopamine Derivatives Featuring a Seco-Benzene System from the Insects Aspongopus chinensis and Periostracum cicadae.

Aspongamide F (1), a novel N-acetyldopamine (NADA) dimer possessing a 6/6/6 ring system, and (±)-aspongamides G (2) and H (3), rare NADA derivatives with fragmented benzene rings, were isolated from Aspongopus chinensis. (±)-Cicadamides C (4) and D (5), the first 1,4-Benzodioxane NADA dimers featuring a seco-benzene system, and (±)-cicadamides E (6) and F (7), the NADA dimers derivatives, were isolated from Periostracum cicadae. The structures of all compounds were elucidated by spectroscopic analyses and computational methods. A plausible biosynthetic pathway for compounds 1-5 was proposed. The biological assay revealed that (+)-4 and (-)-4 exhibit renal protection in a dose-dependent manner.

Identification of 8 Rare Deleterious Variants in ADAMTS13 by Next-generation Sequencing in a Chinese Population with Thrombotic Thrombocytopenic Purpura.

OBJECTIVE: Thrombotic thrombocytopenic purpura (TTP) is a rare and fatal disease caused by a severe deficiency in the metalloprotease ADAMTS13 and is characterized by thrombotic microangiopathy. The present study aimed to investigate the genes and variants associated with TTP in a Chinese population. METHODS: Target sequencing was performed on 220 genes related to complements, coagulation factors, platelets, fibrinolytic, endothelial, inflammatory, and anticoagulation systems in 207 TTP patients and 574 controls. Subsequently, logistic regression analysis was carried out to identify the TTP-associated genes based on the counts of rare deleterious variants in the region of a certain gene. Moreover, the associations between common variants and TTP were also investigated. RESULTS: ADAMTS13 was the only TTP-associated gene (OR = 3.77; 95% CI: 1.82-7.81; P=3.6×10È¡4) containing rare deleterious variants in TTP patients. Among these 8 variants, 5 novel rare variants that might contribute to TTP were identified, including rs200594025, rs782492477, c.T1928G (p.I643S), c.3336_3361del (p.Q1114Afs*20), and c.3469_3470del (p.A1158Sfs*17). No common variants associated with TTP were identified under the stringent criteria of correction for multiple testing. CONCLUSION: ADAMTS13 is the primary gene related to TTP. The genetic variants associated with the occurrence of TTP were slightly different between the Chinese and European populations.

Prevalence of burnout among perfusionists in China: A nationwide survey.

BACKGROUND: Burnout has gained increasing attention worldwide as a phenomenon that affects health care professionals. However, there is a lack of relevant research about its impact on practitioners in the field of cardiovascular perfusion in China. This study investigated the prevalence of and the factors associated with the burnout affecting perfusionists in mainland China. METHODS: This national cross-sectional study included perfusionists from 31 provinces in mainland China. Participants were asked to complete a self-administered questionnaire, which included three parts: (1) demographic information, (2) work-related information, and (3) dissatisfaction with work and sources of pressure. The levels of burnout were calculated, and logistic regression was used to analyze the factors associated with burnout. RESULTS: The questionnaire, created by the survey program "Questionnaire Star", was sent to 2211 perfusionists in mainland China. A final sample of 1813 perfusionists participated in the survey, with a participation rate of 82.0% (1813/2211). The prevalence of burnout and severe burnout was 86.0% (1559/1813, 95%CI: 84.3%-87.5%) and 13.3% (241/1813, 95%CI: 11.8%-15.0%), respectively. The logistic regression analysis revealed that age [20-29 years, odds ratio (OR) = 1; 30-39 years, OR = 2.009; 40-49 years, OR = 2.220], educational background (bachelor and below, OR = 1; postgraduate, OR = 1.472), and professional background (others, OR = 1; surgery, OR = 1.283; anesthesiology, OR = 2.004) were associated with burnout. We also found that age (20-29 years, OR = 1; 30-39 years, OR = 1.928), professional background (others, OR = 1; surgery, OR = 1.734; anesthesiology, OR = 2.257), annual cardiopulmonary bypass (CPB) case load in the most recent 3 years (< 50, OR = 1; 50-100, OR = 1.613; 100-300, OR = 1.702; ≥300, OR = 2.637), and income level [< 5000 (RMB/month), OR = 1; 5000-10,000, OR = 0.587; 10,000-20,000, OR = 0.366] were associated with severe burnout among perfusionists. CONCLUSIONS: Cardiovascular perfusionists in mainland China experience high rates of burnout. Age, the professional background, annual CPB caseload in the most recent 3 years, and income level are independently associated with the burnout rates experienced by these health care professionals.

The low hemoglobin levels were associated with mortality in post-cardiotomy patients undergoing venoarterial extracorporeal membrane oxygenation.

BACKGROUND: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is used as a rescue strategy for patients with refractory post-cardiotomy cardiogenic shock (PCS). These patients often have varying degrees of reduced hemoglobin levels, and there are few detailed investigations about the impact of hemoglobin level on their mortality. The objective of this study was to evaluate whether hemoglobin levels at day 1 from VA-ECMO initiation were associated with in-hospital mortality. METHODS: We performed a retrospective analysis of adult VA-ECMO patients over approximately a 2-year period. We divided patients into survival and death groups based on their clinical outcomes and compared the differences in parameters between the two groups. Multivariate logistic regression analyses were performed to estimate whether hemoglobin level was related to the mortality. RESULTS: One hundred and sixteen patients were included in final analysis. There were 52 patients in the survival group and 64 in the death group. The patients were younger in the survival group than the death group (58 vs 63, p = .023). The median (IQR) hemoglobin level at day 1 was 80 (73-89) × g/L, and the median (IQR) RelΔ hemoglobin was 41% (32-48%). Survival patients had a higher hemoglobin level at day 1 and a lower RelΔ hemoglobin than the death patients (91 vs 76 g/L, p < .001; 35% vs 45%, p < .001). The multivariable logistic regression analyses showed that the low hemoglobin levels at day 1 were independently associated with in-hospital mortality (OR 0.808; 95% CI, 0.747-0.874; p < .001). The AUROC for hemoglobin level was 0.89 (95% CI, 0.83-0.95) which was better than that of RelΔ hemoglobin (0.77, 95% CI, 0.68-0.86). CONCLUSIONS: In patients receiving VA-ECMO for PCS, the low hemoglobin levels at day 1 were independently associated with in-hospital mortality.

Impact of Nosocomial Infection on in-Hospital Mortality Rate in Adult Patients Under Venoarterial Extracorporeal Membrane Oxygenation After Cardiac Surgery.

Objective: There was no consensus on the impact of nosocomial infection on In-hospital mortality rate in patients receiving ECMO. This study aimed to investigate the impact of nosocomial infection (NI) on In-hospital mortality rate in adult patients receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO) after cardiac surgery. Materials and Methods: This retrospective study included 503 adult patients who underwent VA-ECMO after cardiac surgery. The impact of time-dependent NIs on In-hospital mortality rate within 28 days of ECMO initiation was investigated using a Cox regression model. The cumulative incidence function for death was compared between patients with NIs and those without NIs using a competing risk model. Results: Within 28 days after ECMO initiation, 206 (41.0%) patients developed NIs, and 220 (43.7%) patients died. The prevalence rates of NIs were 27.8% and 20.3% during and after ECMO therapy, respectively. The incidence rates of NIs during and after ECMO therapy were 49‰ and 25‰, respectively. Time-dependent NI was an independent risk factor for predicting death (hazard ratio = 1.05, 95% confidence interval = 1.00-1.11). The cumulative incidence of death in patients with NI was significantly higher than that in patients without NI at each time point within 28 days of ECMO initiation. (Z = 5.816, P = 0.0159). Conclusion: NI was a common complication in adult patients who received VA-ECMO after cardiac surgery, and time-dependent NI was an independent risk factor for predicting mortality in these patients. Using a competing risk model, we confirmed that NIs increased the risk of In-hospital mortality rate in these patients.

Effects of elevated CO2 concentration on cell structure and stress resistance physiology of Setaria italica under drought stress.

The frequency of drought will increase under further warming. The increase in atmospheric CO2 concentration, along with more frequent drought, will affect crop growth. We examined the changes of cell structure, photosynthetic physiology, antioxidant enzymes, osmotic regulatory substances, and yield of foxtail millet (Setaria ita-lica) leaves under different CO2 concentrations (ambient air CO2 concentration and ambient atmospheric CO2 concentration + 200 µmol·mol-1) and water treatment (soil moisture content maintained at 45%-55%, and 70%-80% of field capacity, representing mild drought and normal water condition, respectively). The results showed that elevated CO2 concentration increased the number of starch grains, the area of single starch grains, and the total area of starch grains in the chloroplast of millet mesophyll cells. Under mild drought condition, elevated CO2 concentration increased net photosynthetic rate of millet leaves at the booting stage by 37.9%, but did not affect water use efficiency at this stage. Elevated CO2 concentration increased net photosynthetic rate and water use efficiency of millet leaves under mild drought condition at the filling stage by 15.0% and 44.2%, respectively. Under mild drought condition, elevated CO2 concentration increased the content of peroxidase (POD) and soluble sugar in millet leaves at the booting stage by 39.3% and 8.0%, respectively, but decreased proline content by 31.5%. It increased the content of POD in millet leaves at the filling stage by 26.5% but decreased the content of MDA and proline by 37.2% and 39.3%, respectively. Under mild drought condition, elevated CO2 concentration significantly increased the number of grain spikes by 44.7% and yield by 52.3% in both years compared with normal water condition. The effect of elevated CO2 concentration on grain yield under mild drought conditions was higher than that under normal water condition. Under mild drought conditions, elevated CO2 concentration increased leaf thickness, vascular bundle sheath cross-sectional area, net photosynthetic rate, and water use efficiency of millet, improved the antioxidant oxidase activity, and changed the concentration of osmotic regulatory substances, alleviated the nega-tive effect of drought on foxtail millet, and finally increased the number of grains per ear and yield of foxtail millet. This study would provide a theoretical basis for millet production and sustainable agricultural development in arid areas under future climate change.

Soluble ST2 predicts continuous renal replacement therapy in patients receiving venoarterial extracorporeal membrane oxygenation.

OBJECTIVE: This study aimed to evaluate the relationship between plasma soluble ST2 (sST2) levels 24 h after extracorporeal membrane oxygenation (ECMO) initiation and continuous renal replacement therapy (CRRT) in patients receiving venoarterial ECMO (V-A ECMO) support. METHODS AND RESULTS: Data of patients who received ECMO support for postcardiotomy cardiogenic shock between January 2017 and July 2019 were retrospectively collected from Beijing Anzhen Hospital, Capital Medical University. Ultimately, 116 patients were included in the present study for analysis. The concentration of sST2 was determined by enzyme-linked immunosorbent assay (ELISA). The log10 sST2 levels were higher in patients undergoing CRRT than those who did not (6.06 vs. 6.22, p = 0.019). Patients undergoing CRRT had a lower survival rate than those who did not (32.8% vs. 67.3%, p < 0.001). In the univariate logistic regression analysis, sST2, HCO3-, lactate, and creatinine levels 24 h after ECMO initiation were related to CRRT (p < 0.05). In the multivariate logistic regression analysis, HCO3- and sST2 were identified as independent risk factors for CRRT use in patients undergoing ECMO (p < 0.05). The area under receiver operator characteristic curve (AUC) for sST2 and HCO3- together was 0.72 (95% confidence interval (CI), 0.79-0.91), which was better than those of sST2 or HCO3- alone (0.63 vs. 0.67). CONCLUSIONS: sST2 and HCO3-levels at 24 h after ECMO initiation were associated with CRRT and could predict CRRT use in postcardiotomy cardiogenic shock patients undergoing ECMO.

Intrinsic Anti-Freezing and Unique Phosphorescence of Glassy Hydrogels with Ultrahigh Stiffness and Toughness at Low Temperatures.

Most hydrogels become frozen at subzero temperatures, leading to degraded properties and limited applications. Cryoprotectants are massively employed to improve anti-freezing property of hydrogels; however, there are accompanied disadvantages, such as varied networks, reduced mechanical properties, and the risk of cryoprotectant leakage in aqueous conditions. Reported here is the glassy hydrogel having intrinsic anti-freezing capacity and excellent optical and mechanical properties at ultra-low temperatures. Supramolecular hydrogel of poly(acrylamide-co-methacrylic acid) with moderate water content (≈50 wt.%) and dense hydrogen-bond associations is in a glassy state at room temperature. Since hydrogen bonds become strengthened as the temperature decreases, this gel becomes stronger and stiffer, yet still ductile, with Young's modulus of 900 MPa, tensile strength of 30 MPa, and breaking strain of 35% at -45 °C. This gel retains high transparency even in liquid nitrogen. It also exhibits unique phosphorescence due to presence of carbonyl clusters, which is further enhanced at subzero temperatures. Further investigations elucidate that the intrinsic anti-freezing property is related to a fact that most water molecules are tightly bound and confined in the glassy matrix and become non-freezable. This correlation, as validated in several systems, provides a roadmap to develop intrinsic anti-freezing hydrogels for widespread applications at extreme conditions.

The function of the phytoplasma effector SWP12 depends on the properties of two key amino acids.

Phytoplasmas are insect-borne bacterial pathogens capable of secreting effectors into host cells and interfering with host plant defense response processes. Previous studies have found that the Candidatus Phytoplasma tritici effector SWP12 binds to and destabilizes the wheat transcription factor TaWRKY74, increasing wheat susceptibility to phytoplasmas. Here, we used a Nicotiana benthamiana transient expression system to identify two key functional sites of SWP12 and screened a series of truncated mutants and amino acid substitution mutants to determine whether they inhibit Bax-induced cell death. Using a subcellular localization assay and online structure analysis websites, we found that structure rather than intracellular localization probably affects the function of SWP12. D33A and P85H are two inactive substitution mutants, neither of which interacts with TaWRKY74, and P85H does not inhibit Bax-induced cell death, suppress flg22-triggered reactive oxygen species (ROS) bursts, degrade TaWRKY74, or promote phytoplasma accumulation. D33A can weakly suppress Bax-induced cell death and flg22-triggered ROS bursts and degrade a portion of TaWRKY74 and weakly promote phytoplasma accumulation. S53L, CPP, and EPWB are three SWP12 homolog proteins from other phytoplasmas. Sequence analysis revealed that D33 was conserved in these proteins, and they exhibited the same polarity at P85. Transient expression in N. benthamiana showed that these proteins could inhibit Bax-induced cell death and suppress ROS bursts. Our findings clarified that P85 and D33 of SWP12 play critical and minor roles, respectively, in suppressing the plant defense response and that they play a preliminary role in determining the functions of homologous proteins.

Engineering viscoelastic mismatch for temporal morphing of tough supramolecular hydrogels.

Viscoelasticity is a generic characteristic of soft biotissues and polymeric materials, endowing them with unique time- and rate-dependent properties. Here, by spatiotemporally tailoring the viscoelasticity in tough supramolecular hydrogels, we demonstrate reprogrammable morphing of the gels based on differential viscoelastic recovery processes that lead to internal strain mismatch. The spatial heterogeneity of viscoelasticity is encoded through integrating dissimilar hydrogels or by site-specific treatment of a singular hydrogel. The temporal morphing behavior of tough gels, including a fast deformation process and then a slow shape-recovery process, is related to the kinetics of associative interactions and the entropic elasticity of supramolecular networks after pre-stretching and release, which takes place spontaneously in the absence of external stimuli. Such a kinetically driven morphing mechanism resolves the trade-off between the mechanical robustness and shape-changing speed in tough hydrogels with dense entanglements and physical associations, and should be applicable to other viscoelastic materials. A numerical theory for the temporal morphing of tough supramolecular gels has been formulated by dynamic coupling of viscoelastic recovery and mechanics of deformations, which is further implemented to predict the sophisticated morphed structures. Furthermore, magnetic particles are incorporated into the morphed tough hydrogels to devise versatile soft actuators and robots for specific applications.