Mechanisms of chloride to promote the uptake and accumulation of cadmium in rice (Oryza sativa L.)

Cadmium (Cd) contamination in rice ecosystems posed a critical challenge to global food security and environmental health. This study aimed to unveil the key mechanisms trough hydroponic experiments by which chloride (Cl-) promoted the absorption and accumulation of cadmium (Cd) in rice plants. The findings elucidated that the addition of Cl- increased Cd uptake by rice roots (5.1 % ∼ 61 %), acting both directly by enhancing root morphology and indirectly through regulating of the main transporter genes of Cd. The study unveiled that Cl- addition significantly improves Cd bioavailability in roots, which was discernible through the augmentation of Cd concentration and proportion in subcellular fractions, coupled with elevated energy values in key cellular components. Moreover, Cl- addition further augmented the intricate process of Cd transport from roots to shoots (16.1- 86.7 %), which was mainly attributed to the underexpression of OsHMA3 and the decrease in the formation of sulfuhydryl substances. This research provides a comprehensive understanding of the complex mechanisms governing Cd dynamics in rice plants in the presence of Cl-. By elucidating these processes, our findings not only contribute to fundamental knowledge in plant metal uptake but also hold promising implications for mitigating Cd contamination in rice cultivation systems.

Foliar Application of Nanoparticles Reduced Cadmium Content in Wheat (Triticum aestivum L.) Grains via Long-Distance "Leaf-Root-Microorganism" Regulation

Foliar application of beneficial nanoparticles (NPs) exhibits potential in reducing cadmium (Cd) uptake in crops, necessitating a systematic understanding of their leaf-root-microorganism process for sustainable development of efficient nano-enabled agrochemicals. Herein, wheat grown in Cd-contaminated soil (5.23 mg/kg) was sprayed with different rates of four commonly used NPs, including nano selenium (SeNPs)/silica (SiO2NPs)/zinc oxide/manganese dioxide. SeNPs and SiO2NPs most effectively reduced the Cd concentration in wheat grains. Compared to the control, Cd concentration in grains was significantly decreased by 35.0 and 33.3% by applying 0.96 mg/plant SeNPs and 2.4 mg/plant SiO2NPs, and the grain yield was significantly increased by 33.9% with SeNPs application. Down-regulated gene expression of Cd transport proteins (TaNramp5 and TaLCT1) and up-regulated gene expression of vacuolar Cd fixation proteins (TaHMA3 and TaTM20) were observed with foliar SeNPs and SiO2NPs use. SeNPs increased the levels of leaf antioxidant metabolites. Additionally, foliar spray of SeNPs resulted in lower abundances of rhizosphere organic acids and reduced Cd bioavailability in rhizosphere soil, and soil microorganisms related to carbon and nitrogen (Solirubrobacter and Pedomicrobium) were promoted. Our findings underscore the potential of the foliar application of SeNPs and SiO2NPs as a plant and rhizosphere soil metabolism-regulating approach to reduce Cd accumulation in wheat grains.

Nano-biochar uptake and translocation by plants: Assessing environmental fate and food chain risk

Nano-biochar (N-BC) is an emerging nanomaterial with potential applications in various fields. Understanding its behavior in the environment and its interaction with plants is crucial for assessing its ecological implications and potential risks to the food chain. In this study, we investigated the absorption and transportation of N-BC by wheat and Chinese cabbage plants using microscopy techniques and stable isotope analysis. Our results revealed that N-BC particles were readily absorbed by the plants through their root systems and transported to the aboveground tissues. Scanning electron microscopy and transmission electron microscopy provided visual evidence of N-BC particles inside the plants, predominantly located in the xylem and cell walls of the cortical tissue. Stable isotope analysis confirmed the uptake and transportation of N-BC, with elevated isotopic values observed in the plant tissues exposed to 13C-N-BC. Our results demonstrated that around 50.2 %-52.4 % of the absorbed N-BC by plants was accumulated in the roots of wheat and Chinese cabbage, and the remaining fraction was transferred to the shoots including steam (31.0 %-32.1 %) and leaf (16.5 %-17.6 %). Importantly, we observed significant accumulation of N-BC in the edible parts of Chinese cabbage, raising concerns about its potential entry into the food chain and associated health risks. These findings highlight the need for further research to explore the specific pathways and modes of N-BC uptake and transport in plants. Monitoring the presence of N-BC in the environment and its potential impact on the food chain is crucial for ensuring food security and safeguarding human health.

Foliar application of selenium nanoparticles alleviates cadmium toxicity in maize (Zea mays L.) seedlings: Evidence on antioxidant, gene expression, and metabolomics analysis

The molecular and metabolic mechanisms of foliar selenium (Se) nanoparticles (SeNPs) application in mitigating cadmium (Cd) toxicity in crops have not been well studied. Herein, hydroponically cultured maize seedlings were exposed to Cd (20 μM) and treated without and with foliar SeNPs application. Effects of SeNPs on Cd transporter genes and plant metabolism were also explored. Results showed that compared to control plants without Cd exposure, Cd exposure decreased shoot height (16.8 %), root length (17.7 %), and fresh weight of root (24.2 %), stem (28.8 %), and foliar-applied leaves (Se-leaves) (15.0 %) via oxidative damage. Compared to Cd exposure alone, foliar SeNPs application at 20 mg/L (0.25 mg/plant) significantly alleviated the Cd toxicity by promoting photosynthesis and antioxidant capacity and fixing Cd in cell wall. Meanwhile, the mineral concentration of Ca (26.0 %), Fe (55.4 %), Mg (27.0 %), Na (28.6 %), and Zn (10.1 %) in Se-leaves was improved via foliar SeNPs application at 20 mg/L. QRT-PCR analysis further revealed that down- and up-regulation of the expression of ZmHMA2 and ZmHMA3 gene in Se-leaves contributed to reduced translocation of Cd in plants and enhanced Cd sequestration in the vacuole, respectively. Metabolomic results further indicated that metabolic pathways including carbohydrate metabolism, membrane transport, translation, amino acid metabolism, and energy metabolism were significantly affected by foliar SeNPs application. In conclusion, foliar SeNPs application at 20 mg/L could be a prospective strategy to mitigate Cd toxicity in maize.

Amendment of organic acids significantly enhanced hydroxyl radical production during oxygenation of paddy soils

Recently, hydroxyl radical (^•OH) production during soil redox fluctuations has been increasingly reported, but the low efficiency of contaminant degradation is the barrier for engineering remediation. The widely distributed low-molecular-weight organic acids (LMWOAs) might greatly enhance ^•OH production due to their strong interactions with Fe(II) species, but it was less investigated. Herein, we found that LMWOAs amendment (i.e., oxalic acid (OA) and citric acid (CA)) significantly enhanced ^•OH production by 1.2 -19.5 times during oxygenation of anoxic paddy slurries. Compared with OA and acetic acid (AA) (78.4 -110.3 μM), 0.5 mM CA showed the highest ^•OH accumulation (140.2 μM) due to the elevated electron utilization efficiency derived from its strongest capacity for complexation. Besides, increasing CA concentrations (within 6.25 mM) dramatically enhanced the ^•OH production and imidacloprid (IMI) degradation (increased by 48.6%), and further decreased due to the extensive competition from excess CA. Compared to 0.5 mM CA, the synergistic effects of acidification and complexation induced by 6.25 mM CA rendered more formation of exchangeable Fe(II) that easily coordinated with CA, and thus significantly enhanced its oxygenation. This study proposed promising strategies for regulating natural attenuation of contaminants using LMWOAs in agricultural fields, especially soils with frequent occurrence of redox fluctuations.

Catch bond models may explain how force amplifies TCR signaling and antigen discrimination

The TCR integrates forces in its triggering process upon interaction with pMHC. Force elicits TCR catch-slip bonds with strong pMHCs but slip-only bonds with weak pMHCs. We develop two models and apply them to analyze 55 datasets, demonstrating the models' ability to quantitatively integrate and classify a broad range of bond behaviors and biological activities. Comparing to a generic two-state model, our models can distinguish class I from class II MHCs and correlate their structural parameters with the TCR/pMHC's potency to trigger T cell activation. The models are tested by mutagenesis using an MHC and a TCR mutated to alter conformation changes. The extensive comparisons between theory and experiment provide model validation and testable hypothesis regarding specific conformational changes that control bond profiles, thereby suggesting structural mechanisms for the inner workings of the TCR mechanosensing machinery and plausible explanations of why and how force may amplify TCR signaling and antigen discrimination.

Analysis of patient-reported outcomes in the approval of novel oncology drugs in the United States, 2017-2022

Background

With the growing notion of patient-focused drug development, the quality of life and other patient-reported outcomes (PROs) of cancer patients are gaining considerable attention. Several drug regulatory agencies, including the U.S. Food and Drug Administration (FDA), are calling attention to PROs. This review aims to comprehensively characterise the application of PROs and regulatory considerations for PROs in the FDA-approved novel oncology drugs.

Methods

The FDA review documents and labels for novel oncology drugs approved from July 2017 to July 2022 were retrieved. We collected and analysed drug approval information, types of endpoints for PROs, PRO measures, designs of trials including PROs, and regulatory comments on PRO-related contents.

Findings

Results demonstrated that PROs were used more commonly for solid tumours than hematologic malignancies, which might be correlated with the disease characteristics. We further categorised and analysed existing PRO measures, providing insight for tool selection in future oncology trial design. Our findings also indicated that PROs currently do not play a significant role in oncology drug approvals. The major deficiencies related to PROs commented on by FDA reviewers were analysed, followed by recommendations for improvements.

Interpretation

This review demonstrates that PROs currently do not play a significant role in oncology drug marketing review, and how they can be used to support the approval of new oncology drugs is still in the exploratory stage. This current situation is not only related to the deficiencies in the design and implementation of PRO-related contents in oncology trials, but more importantly, it is a reminder that we should pay more attention to patient experience in the development of oncology drugs.

Funding

This study was not supported by any funding.

Constructing spike-like energy band alignment at the heterointerface in highly efficient perovskite solar cells

The interface between the absorber and transport layers is shown to be critical for highly efficient perovskite solar cells (PSCs). The undesirable physical and chemical properties of interfacial layers often cause unfavorable band alignment and interfacial states that lead to high charge-carrier recombination and eventually result in lower device performance. Herein, we demonstrate a simple and effective strategy to improve the performance of PSCs by constructing a conduction band offset (CBO) with a small spike, through the inductive effect induced by an organic small molecule. As a result, the modified devices show an enhancement in all photovoltaic performance characteristics with a power conversion efficiency (PCE) increase of 10.6% and retaining more than 94% of its initial PCE after 1800 h of exposure to N₂. Importantly, we find that a moderate spike-like CBO at the interface between the perovskite film and hole transport layer facilitates rapid charge-carrier injection in devices and reduces charge recombination at the interface, thereby increasing the open-circuit voltage and fill factor. Furthermore, a large spike barrier at the interface increases device resistance, leading to a reduced fill factor. Our present work provides valuable information for understanding the influence of a spike-like CBO on charge-carrier dynamics to further improve the performance and stability of PSCs.

Effect of metal cations on antimicrobial activity and compartmentalization of silver in Shewanella oneidensis MR-1 upon exposure to silver ions

Silver is an antimicrobial agent that is used extensively in consumer products, such as fabrics and humidifiers. Silver ion (Ag⁺) uptake in bacteria represents a crucial phase of antimicrobial activity. However, the uptake mechanism of Ag⁺ in bacteria remains largely unknown. The genus Shewanella drives many geochemical processes of nutrients and pollutants in soils. In the present study, Ag⁺ uptake by Shewanella oneidensis MR-1 was first investigated in a laboratory in defined anaerobic, oligotrophic, and inorganic media with or without cations (potassium ions [K⁺], magnesium ions [Mg²⁺], and zinc ions [Zn²⁺]). Our results revealed variations in antimicrobial activity of Ag⁺ in the presence of Mg²⁺ and Zn²⁺. First, Mg²⁺ significantly decreased antimicrobial activity of Ag⁺ in S. oneidensis MR-1 by inhibiting cellular Ag⁺ uptake when compared with K⁺. The results were consistent with that of Co²⁺ (Mg²⁺ channel blocker) decreased Ag⁺ uptake by S. oneidensis MR-1. Moreover, Mg²⁺ promoted riboflavin secretion and facilitated the formation of metallic Ag nanoparticles on bacterial surfaces, which was beneficial for extracellular electron transfer and consequently reduced antibacterial activity of Ag⁺. Second, Zn²⁺ increased the antimicrobial activity of Ag⁺ in S. oneidensis MR-1, although the effect on Ag⁺ uptake was minimal. A synergistic interaction between Zn²⁺ and Ag⁺ led to an increase in dead cells and decreased ferrihydrite reduction capacity. The findings suggest that Mg²⁺ could reduce the environmental risk of Ag⁺ to soil bacteria, while Zn²⁺ should be of particular concern due to its synergistic antimicrobial effect on bacteria.

[Clinicopathological features of spinal solitary fibrous tumor]

Objective: To investigate the clinicopathological, molecular genetic, immunohistochemical and prognostic features of spinal solitary fibrous tumor (SFT). Methods: The clinical data of 12 cases of spinal SFT in Beijing Tsinghua Changgung Hospital, Affiliated to Tsinghua University, diagnosed from January 2015 to December 2021 were collected and reclassified. The clinical data, histopathology, immunohistochemistry and molecular genetics were analyzed. Follow-up and related literature reviews were conducted. Results: Among the 12 patients, there were 5 males and 7 females; the age ranged from 31 to 73 years, with a median age of 50.5 years. All 12 cases were primary tumors, including 4 cases diagnosed at the first time and 8 recurrent cases. Among the 12 cases, 8 were WHO grade 1, 3 were WHO grade 2, and 1 was WHO grade 3. Microscopically, the spinal SFT appeared as a spindle cell tumor, the stroma was rich in many thin-walled blood vessels with various histological features such as cell morphology and necrosis according to the different tumor grade. All (12/12) of the cases expressed vimentin and STAT6 (diffuse and strong nuclear stain), 11 cases (11/12) expressed both CD34 and bcl-2, and 7 cases (7/12) expressed CD99. Next-generation sequencing showed that 12 (12/12) of the patients had NAB2-STAT6 gene fusion. The 12 patients were followed up for 6 to 80 months. There were no recurrences or metastases in the 4 first cases after operation. Among the 8 recurrent cases, 2 of the patients relapsed and 2 died. Conclusions: Spinal SFT is rare and has a high recurrence tendency. Many aspects need to be considered in the diagnosis process. STAT6 is a relatively specific marker for the diagnosis of this tumor. Complete surgical resection is the preferred treatment while postoperative radiotherapy is recommended to reduce tumor recurrence.

Serologic response and safety of COVID-19 vaccination in HSCT or CAR T-cell recipients: a systematic review and meta-analysis

Background

Patients receiving hematopoietic stem cell transplantation (HSCT) or chimeric antigen receptor T cell (CAR T-cell) therapy are immunocompromised and at high risk of viral infection, including SAR2-CoV-2 infection. However, the effectiveness and safety of COVID-19 vaccines in these recipients is not well characterized. The present meta-analysis evaluated the serologic response and safety of COVID-19 vaccines in these population.

Methods

Literature databases (MEDLINE, EMBASE, Web of Science, MedRvix and BioRvix) were searched for original studies with serologic response post COVID-19 vaccination in HSCT or CAR T-cell recipients published until July 14, 2022. The analysis included 27 observational studies with a total of 2899 patients receiving allogeneic HSCT (2506), autologous HSCT (286) or CAR T-cell therapy (107), and 683 healthy participants with serologic response data. Random effects models were used to pool the rate of serologic response to COVID-19 vaccination in HSCT or CAR T-cell recipients and odds ratio comparing with healthy controls.

Results

The pooled seropositivity rates in HSCT and CAR T-cell recipients were 0.624 [0.506–0.729] for one dose, 0.745 [0.712–0.776] for two doses. The rates were significantly lower than those in healthy controls (nearly 100%). In subgroup analysis, CAR T-cell recipients exhibited an even lower seroconversion rate (one dose: 0.204 [0.094–0.386]; two doses: 0.277 [0.190–0.386]) than HSCT counterparts (one dose: 0.779 [0.666–0.862]; two doses: 0.793 [0.762–0.821]). The rates were comparable between autologous and allogeneic HSCT recipients. Other possible impact factors related to seropositivity were time interval between therapy and vaccination, use of immunosuppressive drugs and immune cell counts. Most vaccine-related adverse effects were mild and resolvable, comparable to general population.

Conclusions

This analysis revealed a diminished response to COVID-19 vaccines in HSCT or CAR T-cell recipients. Our findings may inform regular COVID-19 vaccination at appropriate intervals after HSCT or CAR T-cell therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40164-022-00299-6.

Biotic Process Dominated the Uptake and Transformation of Ag+ by Shewanella oneidensis MR-1

Silver ions (Ag⁺) directly emitted from industrial sources or released from manufactured Ag nanoparticles (AgNPs) in biosolid-amended soils have raised concern about the risk to ecosystems. However, our knowledge of Ag⁺ toxicity, internalization, and transformation mechanisms to bacteria is still insufficient. Here, we combine the advanced technologies of hyperspectral imaging (HSI) and single-particle inductively coupled plasma mass spectrometry to visualize the potential formed AgNPs inside the bacteria and evaluate the contributions of biological and non-biological processes in the uptake and transformation of Ag⁺ by Shewanella oneidensis MR-1. The results showed a dose-dependent toxicity of Ag⁺ to S. oneidensis MR-1 in the ferrihydrite bioreduction process, which was primarily induced by the actively internalized Ag. Moreover, both HSI and cross-section high-resolution transmission electron microscopy results confirmed that Ag inside the bacteria existed in the form of particulate. The Ag mass distribution in and around live and inactivated cells demonstrated that the uptake and transformation of Ag⁺ by S. oneidensis MR-1 were mainly via biological process. The bioaccumulation of Ag⁺ may be lethal to bacteria. A better understanding of the uptake and transformation of Ag⁺ in bacteria is central to predict and monitor the key factors that control Ag partitioning dynamics at the biointerface, which is critical to develop practical risk assessment and mitigation strategies.

[Induction of peripheral blood mononuclear cells to hepatocyte-like cells and preliminary study of cell response to injury under the effect of acetaminophen]

Objective: To establish a method for the induction of peripheral blood mononuclear cells to hepatocyte-like cells, and preliminarily investigate cell response to injury under the effect of acetaminophen (APAP). Methods: The surface marker CD45 of peripheral blood mononuclear cells wase detected cells by using flow cytometry and immunofluorescence methods. The cellular morphology of induced hepatocyte-like cells was observed under an inverted microscope. Real-time fluorescent quantitative PCR (RT-PCR) was used to detect the expression level of hepatocyte-specific genes, such as cytochrome (CY) P1A2, CYP3A4, CYP2C9, albumin (ALB), alpha-fetoprotein (AFP), and hepatocyte nuclear factor (HNF)4α mRNA. Immunofluorescence method was used to detect intracellular hepatocyte markers AFP, HNF4α, and ALB expression at the protein level. Biochemical analyzer was used to detect hepatocyte-specific secretory functions of AFP, ALB, and urea. Luciferase chemiluminescence method was used to detect the activity of key drug metabolizing enzyme CYP3A4. Colorimetric assay was used to detect the effect of the drug acetaminophen on hepatocyte-like cells, and alanine aminotransferase (ALT) was used as an indicator of liver cell injury. The statistical differences between the data were compared with t-test and rank-sum test. Results: The positive expression rate of CD45 cell surface markers isolated from peripheral blood mononuclear cells was about 98%, and hepatocyte-like cell morphology changes appeared on 15th day of induction. Compared with isolated mononuclear cells, CYP1A2, CYP3A4, CYP2C9, ALB, AFP and HNF4α mRNA was markedly elevated. The expression level of AFP, ALB and HNF4α protein were equally increased, and the secretory function of AFP, ALB and urea were enhanced. Compared with primary hepatocytes, CYP1A2, CYP2C9, AFP, HNF4α mRNA, and CYP3A4 mRNA did not decrease. The expression levels of AFP, ALB, and HNF4α proteins in the cells did not decrease, and the secretory function of AFP, ALB, and urea did not decrease. In addition, the CYP3A4 enzyme activity produced by hepatocyte-like cells was similar to that of primary hepatocytes. Compared with hepatocyte-like cells incubated without APAP, hepatocyte-like cells incubated with APAP had higher ALT level. Under the effect of APAP, the ALT level of hepatocyte-like cells was higher than isolated mononuclear cells. Conclusion: Peripheral blood mononuclear cells can be induced into hepatocyte-like cells with partial characteristics of hepatocytes, including the activity of CYP3A4, a key enzyme of hepatocyte drug metabolism. Additionally, preliminarily ALT secretory features reflect the hepatocytes injury under the effect of acetaminophen.

Staphylococcus aureus specific lung resident memory CD4+ Th1 cells attenuate the severity of influenza virus induced secondary bacterial pneumonia

Staphylococcus aureus is a major cause of severe pulmonary infections. The evolution of multi-drug resistant strains limits antibiotic treatment options. To date, all candidate vaccines tested have failed, highlighting the need for an increased understanding of the immunological requirements for effective S. aureus immunity. Using an S. aureus strain engineered to express a trackable CD4⁺ T cell epitope and a murine model of S. aureus pneumonia, we show strategies that lodge Th1 polarised bacterium specific CD4⁺ tissue resident memory T cells (Trm) in the lung can significantly attenuate the severity of S. aureus pneumonia. This contrasts natural infection of mice that fails to lodge CD4⁺ Trm cells along the respiratory tract or provide protection against re-infection, despite initially generating Th17 bacterium specific CD4⁺ T cell responses. Interestingly, lack of CD4⁺ Trm formation after natural infection in mice appears to be reflected in humans, where the frequency of S. aureus reactive CD4⁺ Trm cells in lung tissue is also low. Our findings reveal the protective capacity of S. aureus specific respiratory tract CD4⁺ Th1 polarised Trm cells and highlight the potential for targeting these cells in vaccines that aim to prevent the development of S. aureus pneumonia.

Risk factors and prevention of postoperative pancreatic fistula after insulinoma enucleation:a retrospective study from a high-volume center

BACKGROUND/OBJECTIVES

Enucleation is an effective surgical method to treat pancreatic insulinoma, however, the incidence of clinically relevant postoperative pancreatic fistula (CR-POPF) is high. We aim to investigate the risk factors for CR-POPF which have not been well characterized and develop effective methods to prevent CR-POPF after enucleation.

METHODS

This retrospective cohort study included 161 patients diagnosed with insulinoma from June 2016 to July 2020 in Peking Union Medical College Hospital. The risk factors for CR-POPF were evaluated and the role of prophylactic pre-operative pancreatic stent to prevent the occurrence of CR-POPF after enucleation of pancreatic insulinoma were explored.

RESULTS

A cohort of 161 insulinoma cases were reviewed. The CT or MRI imaging reports could be tracked in 108 cases. A total of 96 patients underwent surgery, while 81 experienced pancreatic enucleation. Univariate and multivariate analyses showed that the distance from insulinoma to the main pancreatic duct (MPD) ≤2 mm was an independent risk factor for CR-POPF (p = 0.003, OR = 6.011, 95% Cl 1.852-19.512). The pre-operative pancreatic stent substantially reduced the incidence of CR-POPF in patients with tumor located in proximity to (distance ≤2 mm) the MPD (CR-POPF of the stented group vs the non-stented group: 37.5% vs 71.4%, p = 0.028).

CONCLUSIONS

The distance from insulinoma to MPD ≤2 mm is a predictive factor for CR-POPF after enucleation. Pancreatic duct stenting may benefit patients with insulinoma in proximity to the MPD by enabling a lower CR-POPF rate, so it should be considered before the enucleation of the insulinoma in proximity to the MPD (distance ≤2 mm).

Cooperative ectodomain interaction among TCRαβ, CD3δɛ and CD3γɛ

The T-cell receptor (TCR) complex comprises of the ligand-binding subunit TCRαβ, and the signaling subunits CD3δɛ, CD3γɛ and CD3ζζ, with the Cα/Cβ in proximity to both CD3δɛ and CD3γɛ extracellularly. Direct measurements of the ectodomain interactions had not been successful, although they are believed to be important for TCR stability and functionality. Mechanical force has been shown to modulate TCR–ligand interactions. The TCR mechanosensor hypothesis predicts that force-encoded information may transmit from pMHC to CD3 via TCR-CD3 interaction. Evaluating ectodomain interactions among TCRαβ, CD3δɛ and CD3γɛ can help elucidate the TCR triggering mechanism and further guide the design of TCR-based immunotherapy.

Using two mechanical based assays, we were able to measure the weak two-dimensional (2D) affinities among ectodomains of human TCRαβ (2B4-LC13), and human CD3δɛ or CD3γɛ and showed catch bond formation where lifetimes of TCRαβ–CD3δɛ and TCRαβ–CD3γɛ bonds are prolonged by forces <15 pN. Remarkably, CD3δɛ and CD3γɛ bind TCRαβ cooperatively, forming more bonds that last longer when both CD3s interact with TCRαβ as a whole than the sum of either CD3 interacting with TCRαβ individually. Interestingly, these measurements are comparable to 2D affinity and force-dependent bond lifetime of the 2B4 TCR interaction with its cognate ligand K5:I-Ek, supporting their relevance to TCR function. Using molecular dynamics simulations based on a published Cryo-EM structure, we identified the formation of long-lasting CD3δɛ–TCRαβ–CD3γɛ trimolecular bonds as the structural mechanisms of the cooperativity. Our work helps explain TCR function under force and suggests strategies for engineering of TCR for immunotherapy applications.

Engineering T cells with improved TCR-CD3 interaction for optimal tumor killing

T cell activation requires extracellular stimulatory signals mainly mediated by T cell receptor complex (TCR/CD3). Obtaining detailed mechanistic knowledge of the TCR-mediated signaling pathway holds significant importance in understanding immune diseases, formulating new immunotherapies, and overcoming immunosuppression in current therapies. Here, we used a novel strategy to overcome ineffective anti-tumor responses by modifying the TCR interaction with CD3 subunits without affecting the binding affinity and/or specificity of the TCR-antigen interaction. Based on NMR and mutational studies, we introduced specific alanine mutations in the Cβ helix 3 and Cβ helix 4 – F strand of the TCR extracellular domain. We demonstrated varied functionality in terms of IL-2 production as well as altered bond lifetime measured by biomembrane force probe assay (BFP). Selected mutations retained or displayed enhanced CD3 binding ability in a CD3 tetramer assay. Based on these results we generated retroviral TCR libraries by random mutagenesis at specific extracellular TCR-CD3 interaction sites, expressed them in a T cell hybridoma system and selected TCRs with novel binding specificity using soluble CD3γɛ- and CD3δɛ-tetramers. We are currently determining the correlation between CD3 tetramer binding, bond lifetime, and functionality (kinase activity, IL-2 production, and tumor rejection) of selected TCR mutants. By integrating binding data, T cell signaling data, and functional outcomes, we expect to be able to manipulate the human immune system via the extracellular TCR-CD3 interaction site to be utilized in novel human T cell therapies.

Role of Discoidin Domain Receptor 2 in Craniofacial Bone Regeneration

Bone loss caused by trauma, neoplasia, congenital defects, or periodontal disease is a major cause of disability and human suffering. Skeletal progenitor cell-extracellular matrix interactions are critical for bone regeneration. Discoidin domain receptor 2 (DDR2), an understudied collagen receptor, plays an important role in skeletal development. Ddr2 loss-of-function mutations in humans and mice cause severe craniofacial and skeletal defects, including altered cranial shape, dwarfing, reduced trabecular and cortical bone, alveolar bone/periodontal defects, and altered dentition. However, the role of this collagen receptor in craniofacial regeneration has not been examined. To address this, calvarial subcritical-size defects were generated in wild-type (WT) and Ddr2-deficient mice. The complete bridging seen in WT controls at 4 wk postsurgery was not observed in Ddr2-deficient mice even after 12 wk. Quantitation of defect bone area by micro-computed tomography also revealed a 50% reduction in new bone volume in Ddr2-deficient mice. Ddr2 expression during calvarial bone regeneration was measured using Ddr2-LacZ knock-in mice. Expression was restricted to periosteal surfaces of uninjured calvarial bone and, after injury, was detected in select regions of the defect site by 3 d postsurgery and expanded during the healing process. The impaired bone healing associated with Ddr2 deficiency may be related to reduced osteoprogenitor or osteoblast cell proliferation and differentiation since knockdown/knockout of Ddr2 in a mesenchymal cell line and primary calvarial osteoblast cultures reduced osteoblast differentiation while Ddr2 overexpression was stimulatory. In conclusion, Ddr2 is required for cranial bone regeneration and may be a novel target for therapy.

Unresponsiveness to inhaled antigen is governed by conventional dendritic cells and overridden during infection by monocytes

The nasal-associated lymphoid tissues (NALTs) are mucosal-associated lymphoid organs embedded in the submucosa of the nasal passage. NALTs represent a known site for the deposition of inhaled antigens, but little is known of the mechanisms involved in the induction of immunity within this lymphoid tissue. We find that during the steady state, conventional dendritic cells (cDCs) within the NALTs suppress T cell responses. These cDCs, which are also prevalent within human NALTs (tonsils/adenoids), express a unique transcriptional profile and inhibit T cell proliferation via contact-independent mechanisms that can be diminished by blocking the actions of reactive oxygen species and prostaglandin E2. Although the prevention of unrestrained immune activation to inhaled antigens appears to be the default function of NALT cDCs, inflammation after localized virus infection recruited monocyte-derived DCs (moDCs) to this region, which diluted out the suppressive DC pool, and permitted local T cell priming. Accommodating for inflammation-induced temporal changes in NALT DC composition and function, we developed an intranasal vaccine delivery system that coupled the recruitment of moDCs with the sustained release of antigen into the NALTs, and we were able to substantially improve T cell responses after intranasal immunization. Thus, homeostasis and immunity to inhaled antigens is tuned by inflammatory signals that regulate the balance between conventional and moDC populations within the NALTs.

Endocrine and genetic factors affecting egg laying performance in chickens: a review

1. Egg-laying performance reflects the overall reproductive performance of breeding hens. The genetic traits for egg-laying performance have low or medium heritability, and, depending on the period involved, usually ranges from 0.16 to 0.64. Egg-laying in chickens is regulated by a combination of environmental, endocrine and genetic factors. 2. The main endocrine factors that regulate egg-laying are gonadotropin-releasing hormone (GnRH), prolactin (PRL), follicle-stimulating hormone (FSH) and luteinising hormone (LH). 3. In the last three decades, many studies have explored this aspect at a molecular genetic level. Recent studies identified 31 reproductive hormone-based candidate genes that were significantly associated with egg-laying performance. With the development of genome-sequencing technology, 64 new candidate genes and 108 single nucleotide polymorphisms (SNPs) related to egg-laying performance have been found using genome-wide association studies (GWAS), providing novel insights into the molecular genetic mechanisms governing egg production. At the same time, microRNAs that regulate genes responsible for egg-laying in chickens were reviewed. 4. Research on endocrinological and genetic factors affecting egg-laying performance will greatly improve the reproductive performance of chickens and promote the protection, development, and utilisation of poultry. This review summarises studies on the endocrine and genetic factors of egg-laying performance in chickens from 1972 to 2019.

Modulating extracellular TCR-CD3 interaction to identify new immunotherapy targets against cancer

T cell recognition of antigen and resulting proximal signaling are key steps in the initiation of the adaptive immune response. Previous studies targeting antigen binding site for enhancing T-cell responses to tumor antigens often lead to off-target effects and toxicity. Recently, we used nuclear magnetic resonance (NMR) spectroscopy, mutational analysis and computational docking to derive a 3D structure of the extracellular TCR-CD3 assembly. Further, biomolecular force probe (BFP) measurements allowed us to determine how 2D affinity and force-modulated TCR-pMHC kinetics depend on TCR-CD3 interaction sites and affect transduction of extracellular pMHC-TCR ligation into T cell function. Based on our TCR-CD3 structural model and binding data, we generated TCR libraries for a melanoma-specific TCR (DMF5) using site-specific mutagenesis in the Cbhelix 3 and helix 4-F strand regions of the TCR to optimize the TCR-CD3 interaction and to select for mutants with enhanced T-cell effector function. One Cb helix 4-F strand mutant, NP202203AA showed increased T cell response to antigen and showed enhanced TCR-pMHC bond lifetime (catch-bonds) in BFP assays leading to prolonged T cell signaling. In the future, DMF5 TCR with reengineered CD3 binding regions will be used in tumor rejection in pre-clinical mouse melanoma models for efficacy and toxicity to develop more effective T cell therapies for human targets.

The Role of Discoidin Domain Receptor 2 in Tooth Development

Collagen signaling is critical for proper bone and tooth formation. Discoidin domain receptor 2 (DDR2) is a collagen-activated tyrosine kinase receptor shown to be essential for skeletal development. Patients with loss of function mutations in DDR2 develop spondylo-meta-epiphyseal dysplasia (SMED), a rare, autosomal recessive disorder characterized by short stature, short limbs, and craniofacial anomalies. A similar phenotype was observed in Ddr2-deficient mice, which exhibit dwarfism and defective bone formation in the axial, appendicular, and cranial skeletons. However, it is not known if Ddr2 has a role in tooth formation. We first defined the expression pattern of Ddr2 during tooth formation using Ddr2-LacZ knock-in mice. Ddr2 expression was detected in the dental follicle/sac and dental papilla mesenchyme of developing teeth and in odontoblasts and the periodontal ligament (PDL) of adults. No LacZ staining was detected in wild-type littermates. This Ddr2 expression pattern suggests a potential role in the tooth and surrounding periodontium. To uncover the function of Ddr2, we used Ddr2^slie/slie mice, which contain a spontaneous 150-kb deletion in the Ddr2 locus to produce an effective null. In comparison with wild-type littermates, Ddr2^slie/slie mice displayed disproportional tooth size (decreased root/crown ratio), delayed tooth root development, widened PDL space, and interradicular alveolar bone defects. Ddr2^slie/slie mice also had abnormal collagen content associated with upregulation of periostin levels within the PDL. The delayed root formation and periodontal abnormalities may be related to defects in RUNX2-dependent differentiation of odontoblasts and osteoblasts; RUNX2-S319-P was reduced in PDLs from Ddr2^slie/slie mice, and deletion of Ddr2 in primary cell cultures from dental pulp and PDL inhibited differentiation of cells to odontoblasts or osteoblasts, respectively. Together, our studies demonstrate odontoblast- and PDL-specific expression of Ddr2 in mature and immature teeth, as well as indicate that DDR2 signaling is important for normal tooth formation and maintenance of the surrounding periodontium.

A TCR mechanotransduction signaling loop induces negative selection in the thymus

The T cell antigen receptor (TCR) expressed on thymocytes interacts with self-peptide major histocompatibility complex (pMHC) ligands to signal apoptosis or survival. Here, we found that negative-selection ligands induced thymocytes to exert forces on the TCR and the co-receptor CD8 and formed cooperative TCR-pMHC-CD8 trimolecular 'catch bonds', whereas positive-selection ligands induced less sustained thymocyte forces on TCR and CD8 and formed shorter-lived, independent TCR-pMHC and pMHC-CD8 bimolecular 'slip bonds'. Catch bonds were not intrinsic to either the TCR-pMHC or the pMHC-CD8 arm of the trans (cross-junctional) heterodimer but resulted from coupling of the extracellular pMHC-CD8 interaction to the intracellular interaction of CD8 with TCR-CD3 via associated kinases to form a cis (lateral) heterodimer capable of inside-out signaling. We suggest that the coupled trans-cis heterodimeric interactions form a mechanotransduction loop that reinforces negative-selection signaling that is distinct from positive-selection signaling in the thymus.

Programmable Multivalent DNA-Origami Tension Probes for Reporting Cellular Traction Forces

Mechanical forces are central to most, if not all, biological processes, including cell development, immune recognition, and metastasis. Because the cellular machinery mediating mechano-sensing and force generation is dependent on the nanoscale organization and geometry of protein assemblies, a current need in the field is the development of force-sensing probes that can be customized at the nanometer-length scale. In this work, we describe a DNA origami tension sensor that maps the piconewton (pN) forces generated by living cells. As a proof-of-concept, we engineered a novel library of six-helix-bundle DNA-origami tension probes (DOTPs) with a tailorable number of tension-reporting hairpins (each with their own tunable tension response threshold) and a tunable number of cell-receptor ligands. We used single-molecule force spectroscopy to determine the probes' tension response thresholds and used computational modeling to show that hairpin unfolding is semi-cooperative and orientation-dependent. Finally, we use our DOTP library to map the forces applied by human blood platelets during initial adhesion and activation. We find that the total tension signal exhibited by platelets on DOTP-functionalized surfaces increases with the number of ligands per DOTP, likely due to increased total ligand density, and decreases exponentially with the DOTP's force-response threshold. This work opens the door to applications for understanding and regulating biophysical processes involving cooperativity and multivalency.

Changes and analysis of anti-HBs titres after primary immunization in 1- to 16-year-old Chinese children: A hospital-based study

Immunization with the hepatitis B vaccine is the most effective measure to prevent Hepatitis B Virus (HBV) infection. The aim of this study was to investigate the change in antibody levels induced by administration of the hepatitis B vaccine in children aged 1-16 year old in a large sample sized investigation. HBV markers were determined in 93 326 1- to 16-year-old hospitalized children who completed primary immunization as infants from south-west China, Chongqing. Analyses were performed on anti-HBs titre changes with increasing age, and the revaccination effect was evaluated in children aged 7-14. The percentage of protective antibody was between 45.29% and 63.33% in all age groups, but was higher in the 1-, 2- and 3-year-old groups (90.31%, 83.95% and 71.82%, respectively), and the rate of high-responder was 5.03%-10.56%, except in the 1-year-old group (23.33%). Additionally, 3.33%-25.79% of subjects had not seroconverted. There was no significant difference in antibody levels between girls and boys (P > .05). The Geometric Mean Titers in children with confirmed revaccination history were significantly higher than those with unknown or no revaccination history (P < .0001). In conclusion, the overall rate of protective anti-HBs was 67.10% with consecutive age groups from 1 to 16, it decreased from 90.31% to 45.29% for 1- to 8-year-old individuals, and interestingly, the rate increased from 45.46% to 63.33% for subjects aged 9-15. Anti-HBs titres were significantly improved after revaccination. Booster doses are recommended for those without seroconversion, especially children who live in school with other students or have family members with positive HBsAg.

Selective Role of Discoidin Domain Receptor 2 in Murine Temporomandibular Joint Development and Aging

Temporomandibular joint (TMJ) disorders are often associated with development of osteoarthritis-like changes in the mandibular condyle. Discoidin domain receptor 2 (DDR2), a collagen receptor preferentially activated by type I and III collagen found in the TMJ and other fibrocartilages, has been associated with TMJ degeneration, but its role in normal joint development has not been previously examined. Using Ddr2 LacZ-tagged mice and immunohistochemistry, we found that DDR2 is preferentially expressed and activated in the articular zone of TMJs but not knee joints. To assess the requirement for Ddr2 in TMJ development, studies were undertaken to compare wild-type and smallie ( slie) mice, which contain a spontaneous deletion in Ddr2 to produce an effective null allele. Analysis of TMJs from newborn Ddr2^slie/slie mice revealed a developmental delay in condyle mineralization, as measured by micro-computed tomography and histologic analysis. In marked contrast, knee joints of Ddr2^slie/slie mice were normal. Analysis of older Ddr2^slie/slie mice (3 and 10 mo) revealed that the early developmental delay led to a dramatic and progressive loss of TMJ articular integrity and osteoarthritis-like changes. Mutant condyles had a rough and flattened bone surface, accompanied by a dramatic loss of bone mineral density. Mankin scores showed significantly greater degenerative changes in the TMJs of 3- and 10-mo-old Ddr2^slie/slie mice as compared with wild-type controls. No DDR2-dependent degenerative changes were seen in knees. Analysis of primary cultures of TMJ articular chondrocytes from wild-type and Ddr2^slie/slie mice showed defects in chondrocyte maturation and mineralization in the absence of Ddr2. These studies demonstrate that DDR2 is necessary for normal TMJ condyle development and homeostasis and that these DDR2 functions are restricted to TMJ fibrocartilage and not seen in the hyaline cartilage of the knee.

Realization of microbial community stratification for single-stage nitrogen removal in a sequencing batch biofilter granular reactor

A permanent microbial stratified nitrogen removal system coupling anammox with partial nitrification (SNAP) in a sequencing batch biofilter granular reactor (SBBGR) was successfully constructed for the treatment of ammonia-rich wastewater. With a nitrogen loading rate of 0.1kgNm^-3·d^-1, the maximal ammonia and total nitrogen removal efficiencies could reach up to 96.08% and 84.86% on day 108, respectively. The pH, DO profiles revealed a switch of functional species (AOB and anammox) at a typical intermittent aeration cycle. qPCR and high throughput analyses certified a stable spatial microbial stratified community structure. Although, anammox preferred strict anaerobic environment while AOB needed oxygen, a special stratified community structure contributed to conquer this obstacle. Moreover, Bacteroidet, Chlorobi, OD1, Planctomycetes, and Proteobacteria were the dominant species in the SBBGR. Although we have predicted the possible pathways of nitrogen transformation, further studies are needed to validate the pathways in enzymology.

Receptor-mediated cell mechanosensing

Mechanosensing depicts the ability of a cell to sense mechanical cues, which under some circumstances is mediated by the surface receptors. In this review, a four-step model is described for receptor-mediated mechanosensing. Platelet GPIb, T-cell receptor, and integrins are used as examples to illustrate the key concepts and players in this process.

Mechanosensing describes the ability of a cell to sense mechanical cues of its microenvironment, including not only all components of force, stress, and strain but also substrate rigidity, topology, and adhesiveness. This ability is crucial for the cell to respond to the surrounding mechanical cues and adapt to the changing environment. Examples of responses and adaptation include (de)activation, proliferation/apoptosis, and (de)differentiation. Receptor-mediated cell mechanosensing is a multistep process that is initiated by binding of cell surface receptors to their ligands on the extracellular matrix or the surface of adjacent cells. Mechanical cues are presented by the ligand and received by the receptor at the binding interface; but their transmission over space and time and their conversion into biochemical signals may involve other domains and additional molecules. In this review, a four-step model is described for the receptor-mediated cell mechanosensing process. Platelet glycoprotein Ib, T-cell receptor, and integrins are used as examples to illustrate the key concepts and players in this process.

Dissimilatory Nitrate Reduction to Ammonium in the Yellow River Estuary: Rates, Abundance, and Community Diversity

Dissimilatory nitrate reduction to ammonium (DNRA) is an important nitrate reduction process in estuarine sediments. This study reports the first investigation of DNRA in the Yellow River Estuary located in Eastern Shandong, China. Saltwater intrusion could affect the physicochemical characteristics and change the microbial community structure of sediments. In this study, the activity, abundance and community diversity of DNRA bacteria were investigated during saltwater intrusion. The slurry incubation experiments combined with isotope-tracing techniques and qPCR results showed that DNRA rates and nrfA (the functional gene of DNRA bacteria) gene abundance varied over wide ranges across different sites. DNRA rates had a positive and significant correlation with sediment organic content and extractable NH₄⁺, while DNRA rates were weakly correlated with nrfA gene abundance. In comparison, the activities and abundance of DNRA bacteria did not change with a trend along salinity gradient. Pyrosequencing analysis of nrfA gene indicated that delta-proteobacteria was the most abundant at all sites, while epsilon-proteobacteria was hardly found. This study reveals that variability in the activities and community structure of DNRA bacteria is largely driven by changes in environmental factors and provides new insights into the characteristics of DNRA communities in estuarine ecosystems.

Identification and characterization of a phospholipase A1 activity type three secreted protein, PP_ExoU from Pseudomonas plecoglossicida NB2011, the causative agent of visceral granulomas disease in large yellow croaker (Larimichthys crocea)

Pseudomonas plecoglossicida NB2011, the causative agent of visceral granulomas disease in farmed Larimichthys crocea in China, encodes a predicted type three effector PP_ExoU, a homolog of the cytotoxin ExoU of Pseudomonas aeruginosa. In this study, secretion of PP_ExoU was tested in various broth, the protein was expressed with the pET30a prokaryotic system, the phospholipase A (PLA) activity of the recombinant protein was determined with fluorogenic phospholipid substrates, fusion expression with green fluorescent protein in transfected HeLa cells was investigated, and the lactate dehydrogenase (LDH) level was measured. The results showed the protein was type three secreted in several media; the recombinant protein displayed significant PLA1 activity with ubiquitin. Fluorescence was observed on the cell membrane and scattered in the cytoplasm of HeLa cells expressing catalytic wild-type PP_ExoU, blebbing and stretching developed in the cell membranes indicating of membrane damage. Fluorescence scattered in the cytoplasm of cells expressing the catalytic inactive protein. A significant LDH level was detected in HeLa cells expressing wild-type PP_exoU, but not in the Ser/Asp-mutated protein, suggestion mutation of predicted catalytic residues abolished the PLA activity. This is the first report on the function of a secreted type three protein from P. plecoglossicida.

Notch-Jagged complex structure implicates a catch bond in tuning ligand sensitivity

Notch receptor activation initiates cell fate decisions and is distinctive in its reliance on mechanical force and protein glycosylation. The 2.5-angstrom-resolution crystal structure of the extracellular interacting region of Notch1 complexed with an engineered, high-affinity variant of Jagged1 (Jag1) reveals a binding interface that extends ~120 angstroms along five consecutive domains of each protein. O-Linked fucose modifications on Notch1 epidermal growth factor-like (EGF) domains 8 and 12 engage the EGF3 and C2 domains of Jag1, respectively, and different Notch1 domains are favored in binding to Jag1 than those that bind to the Delta-like 4 ligand. Jag1 undergoes conformational changes upon Notch binding, exhibiting catch bond behavior that prolongs interactions in the range of forces required for Notch activation. This mechanism enables cellular forces to regulate binding, discriminate among Notch ligands, and potentiate Notch signaling.

Abstract P4-03-03: Microenvironment induced DDR2 mediates stromal-cancer interactions and metastasis growth in breast cancer

This abstract was not presented at the symposium.

ZnO nanosheet-assisted immobilization of Ag nanoparticles on graphene/Ni foam for highly efficient reduction of 4-nitrophenol

ZnO nanosheet-assisted immobilization of Ag nanoparticles on graphene/Ni foam forming a novel hybrid structure for catalysis.

Healing Cranial Defects with AdRunx2-transduced Marrow Stromal Cells

Marrow stromal cells (MSCs) include stem cells capable of forming all mesenchymal tissues, including bone. However, before MSCs can be successfully used in regeneration procedures, methods must be developed to stimulate their differentiation selectively to osteoblasts. Runx2, a bone-specific transcription factor, is known to stimulate osteoblast differentiation. In the present study, we tested the hypothesis that Runx2 gene therapy can be used to heal a critical-sized defect in mouse calvaria. Runx2-engineered MSCs displayed enhanced osteogenic potential and osteoblast-specific gene expression in vitro and in vivo. Runx2-expressing cells also dramatically enhanced the healing of critical-sized calvarial defects and increased both bone volume fraction and bone mineral density. These studies provide a novel route for enhancing osteogenesis that may have future therapeutic applications for craniofacial bone regeneration.

Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

Fertilized soils have large potential for production of soil nitrogen oxide (NO_x=NO+NO₂), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NO_x contributes to formation of tropospheric ozone (O₃), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NO_x emissions in a high-temperature agricultural region of California. We also investigate whether soil NO_x emissions are capable of influencing regional air quality. We report some of the highest soil NO_x emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NO_x emissions and NO_x at the surface and in the troposphere. Adjusting the model to match NO_x observations leads to elevated tropospheric O₃. Our results suggest management can greatly reduce soil NO_x emissions, thereby improving air quality.

Soil NO_x emissions can significantly impact air quality in agricultural regions, particularly high temperature fertilized systems. Here, the authors investigate NO_x emissions in one such system in California and suggest that the NO_x emissions are the highest ever observed, with implications for air quality.

Inactivation of internalized Salmonella Typhimurium in lettuce and green onion using ultraviolet C irradiation and chemical sanitizers

AIMS

The internalized human pathogens in fresh produce are not effectively removed during conventional washing, and therefore, it may cause foodborne illness when the produce is consumed raw. Thus, effective nonthermal processes are needed to prevent this risk.

METHODS AND RESULTS

Green fluorescence protein-tagged Salmonella Typhimurium was either sprayed on the surface of iceberg lettuce or injected into the bottom part (bulb) of green onions to induce bacterial internalization. The contaminated vegetables were collected after 2 days and subjected to surface disinfection. Different fluencies of UV-C radiation (75-900 mJ cm(-2)) and two fluencies of UV-C (450, 900 mJ cm(-2)) combined with chlorine and peracetic acid (PAA) were applied to the produce to examine the inactivation efficiency of internalized bacteria. A range of 1·96-2·52 log reduction in the internalized Salmonella was achieved when the lettuce was treated with higher UV-C fluency (150, 450, 900 mJ cm(-2)) or UV-C combined with chemical disinfectants. Significant reduction (1·00-1·49 log CFU g(-1)) in internalized Salmonella was observed in green onion treated with UV-C with the fluency of 150 or 900 mJ cm(-2) or UV-C-chlorine/PAA. No significant reduction was observed in either lettuce or green onion treatments when chlorine or PAA was used alone. The food quality measured with firmness was not changed during any treatments. However, a slight colour change was observed in lettuce only when UV-C was used at 900 mJ cm(-2).

CONCLUSION

High fluency UV-C can significantly inactivate the internalized Salmonella in lettuce and green onion while maintaining the food quality.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research provides applicable research outcomes for developing nonthermal methods to inactivate internalized pathogens in fresh produce.

Ozonation as a clean technology for fresh produce industry and environment: sanitizer efficiency and wastewater quality

AIMS

Inactivating microbial contaminants in fresh produce commonly uses chlorine washing. The effectiveness of ozone was explored as an alternative to chlorine in produce washing for ensuring microbial safety while maximizing water reusability.

METHODS AND RESULTS

An ozone washing system was designed to permit continuous addition of contaminated produce and the reuse of washing water. The effectiveness of ozonation (<2 mg l(-1) ) was determined using Bacillus subtilis spores as a stricter measure of efficiency with processing time of 10 min. As a comparison, chlorine (c. 100 mg l(-1) ) was tested in parallel. Water quality characteristics, including chemical oxygen demand, total suspended solids, disinfectants concentration and microbial reduction were measured. Ozonation showed an average of 1·56 log reduction of B. subtilis spores on lettuce, while chlorination achieved a 1·30 log reduction. The effluents after ozonation demonstrated improved water quality, both in physicochemical quality and microbial quality compared to chlorination.

CONCLUSION

Aqueous ozone treatment is effective against microbial contaminants on fresh produce and enables extended use of washing water.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results provide significant data about ozone disinfection efficacy and its impact on the water reusability, which can facilitate the ozone utilization in the fresh produce production as an environmental friendly alternative.

Compaction enhances extracellular matrix content and mechanical properties of tissue-engineered cartilaginous constructs

Many cell-based tissue-engineered cartilaginous constructs are mechanically softer than native tissue and have low content and abnormal proportions of extracellular matrix (ECM) constituents. We hypothesized that the load-bearing mechanical properties of cartilaginous constructs improve with the inclusion of collagen (COL) and proteoglycan (PG) during assembly. The objectives of this work were to determine (1) the effect of addition of PG, COL, or COL+PG on compressive properties of 2% agarose constructs and (2) the ability of mechanical compaction to concentrate matrix content and improve the compressive properties of such constructs. The inclusion of COL+PG improved the compressive properties of hydrogel constructs compared with PG or COL alone. Mechanical compaction increased the PG and COL concentrations in and compressive stiffness of the constructs. Chondrocytes included in the constructs maintained high viability after compaction. These results support the concepts that the assembly of cartilaginous constructs with COL+PG and application of mechanical compaction enhance the ECM content and compressive properties of engineered cartilaginous constructs.

Factors associated with occupational strain among Chinese teachers: a cross-sectional study

OBJECTIVES

With the reform of the education system in China, teachers are suffering from more occupational strain, which is believed to impair their working state indirectly and affect their health. This study assessed occupational strain and explored the related factors among Chinese teachers.

STUDY DESIGN

Cross-sectional with cluster sampling.

METHODS

The study population was composed of 3570 school teachers working in 64 primary and middle schools in Heping District in Shenyang, China. Data were collected using a self-administered questionnaire (the Chinese version of the Occupational Stress Inventory scale). Multivariate linear regression analyses were performed to study the factors related to occupational strain.

RESULTS

The average score on the Personal Strain Questionnaire (PSQ) for the whole study population was 106.5 (107.5 in men and 106.3 in women). Teachers with chronic disease, a greater number of days of sick leave, recent experience of a stressful life event and divorced/separated/widowed status tended to suffer greater strain than their peers. Regression analyses showed that the PSQ score was significantly associated with role overload, role boundary, responsibility and physical environment, and inversely associated with recreation and rational coping. The most crucial predictors of occupational strain were chronic disease, days of sick leave, recent experience of a stressful life event and marital status. Being a class teacher was the strongest indicator of interpersonal strain. Self-care was associated with vocational strain and psychological strain, and inversely associated with physical strain.

CONCLUSIONS

Most teachers in this study experienced a high degree of occupational strain. Chronic disease, days of sick leave, recent experience of a stressful life event and divorced/separated/widowed status played prominent roles in occupational strain. In addition, role overload, role boundary, responsibility and physical environment induce occupational strain, while recreation and rational coping have a positive effect on occupational strain. Interventions such as proper management of chronic diseases and establishment of a balanced work-family life are crucial to reduce occupational strain. Recreation and training in coping abilities are needed to enhance positive working environments and attenuate the occupational strain imposed on teachers.