Tensile Strain-Mediated Bimetallene Nanozyme for Enhanced Photothermal Tumor Catalytic Therapy

Nanozymes have demonstrated significant potential in combating malignant tumor proliferation through catalytic therapy. However, the therapeutic effect is often limited by insufficient catalytic performance. In this study, we propose the utilization of strain engineering in metallenes to fully expose the active regions due to their ultrathin nature. Here, we present the first report on a novel tensile strain-mediated local amorphous RhRu (la-RhRu) bimetallene with exceptional intrinsic photothermal effect and photo-enhanced multiple enzyme-like activities. Through geometric phase analysis, electron diffraction profile, and X-ray diffraction, it is revealed that crystalline-amorphous heterophase boundaries can generate approximately 2% tensile strain in the bimetallene. The ultrathin structure and in-plane strain of the bimetallene induce an amplified strain effect. Both experimental and theoretical evidence support the notion that tensile strain promotes multiple enzyme-like activities. Functioning as a tumor microenvironment (TME)-responsive nanozyme, la-RhRu exhibits remarkable therapeutic efficacy both in vitro and in vivo. This work highlights the tremendous potential of atomic-scale tensile strain engineering strategy in enhancing tumor catalytic therapy.

Acute non-traffic traumatic spinal cord injury in the aging population: Analysis of the National Inpatient Sample 2005-2018

BACKGROUND

This study aimed to determine risk factors for poor in-hospital outcomes in a large cohort of older adult patients with acute non-traffic traumatic spinal cord injury (tSCI).

METHODS

This is a population-based, retrospective, observational study. Data of older adults ≥65 years with a primary discharge diagnosis of acute non-traffic tSCI were extracted from the US National Inpatient Sample (NIS) database 2005-2018. Traffic-related tSCI admissions or patients lacking complete data on age, sex and outcomes of interest were excluded. Univariate and multivariate logistic regression analysis was used to determine associations between variables and in-hospital outcomes.

RESULTS

Data of 49,449 older patients (representing 246,939 persons in the US) were analyzed. The mean age was 79.9 years. Multivariable analyses revealed that severe International Classification of Disease (ICD)-based injury severity score (ICISS) (adjusted odds ratio [aOR] = 3.14, 95% confidence interval [CI]: 2.77-3.57), quadriplegia (aOR = 2.79, 95%CI: 2.34-3.32), paraplegia (aOR = 2.60, 95%CI:1.89-3.58), cervical injury with vertebral fracture (aOR = 2.19, 95%CI: 1.90-2.52), and severe liver disease (aOR = 2.33, 95%CI: 1.34-4.04) were all strong independent predictors of in-hospital mortality. In addition, malnutrition (aOR = 3.19, 95% CI: 2.93-3.48) was the strongest predictors of prolonged length of stay (LOS).

CONCLUSIONS

Several critical factors for in-hospital mortality, unfavorable discharge, and prolonged LOS among US older adults with acute non-traffic tSCI were identified. In addition to the factors associated with initial severity, the presence of severe liver disease and malnutrition emerged as strong predictors of unfavorable outcomes, highlighting the need for special attention for these patient subgroups.

Heat Stroke Induces Pyroptosis in Spermatogonia via the cGAS-STING Signaling Pathway

To explore the mechanism whereby cGAS-STING pathway regulates the pyroptosis of cryptorchidism cells, with a view to finding a new strategy for clinically treating cryptorchidism-induced infertility. Spermatogonial GC-1 cells were heat stimulated to simulate the heat hurt microenvironment of cryptorchidism. The cell viability was assayed by CCK-8, and cellular DNA damage was detected by gamma-H2AX immunofluo-rescence assay. Flow cytometry was employed to assess pyroptosis index, while western blot, ELISA and PCR were used to examine the expressions of pyroptosis-related proteins (Caspase-1, IL-1beta, NLRP3) and cGAS-STING pathway proteins (cGAS, STING). After STING silencing by siRNA, the expressions of pyroptosis-related proteins were determined. Pyroptosis occurred after heat stimulation of cells. Morphological detection found cell swelling and karyopyknosis. According to the gamma-H2AX immunofluorescence (IFA) assay, the endonuclear green fluorescence was significantly enhanced, the gamma-H2AX content markedly increased, and the endonuclear DNA was damaged. Flow cytometry revealed a significant increase in pyroptosis index. Western blot and PCR assays showed that the expressions of intracellular pyrogenic proteins like Caspase-1, NLRP3 and GSDMD were elevated. The increased STING protein and gene expressions in cGAS-STING pathway suggested that the pathway was intracellularly activated. Silencing STING protein in cGAS-STING pathway led to significantly inhibited pyroptosis. These results indicate that cGAS-STING pathway plays an important role in heat stress-induced pyroptosis of spermatogonial cells. After heat stimulation of spermatogonial GC-1 cells, pyroptosis was induced and cGAS-STING pathway was activated. This study can further enrich and improve the molecular mechanism of cryptorchidism.

Impact of Frailty on Inpatient Outcomes of Acute Traumatic Spinal Cord Injury: Evidence From US National Inpatient Sample

OBJECTIVES

Spinal cord injury (SCI) is any spinal cord injury or affliction that results in temporary or permanent impairment of motor or sensory function. This study determined the prevalence of frailty and its impact on in-hospital outcomes of patients admitted with acute traumatic SCI (TSCI).

METHODS

This retrospective study extracted data of adults 18 to 85 years with acute TSCI from the US Nationwide Inpatient Sample (NIS) 2016 to 2018. Frailty status were assessed by the 11-factor modified Frailty Index (mFI-11) through claim codes. Patients with an mFI ≥3 were classified as frail. Associations between study variables and in-hospital mortality, discharge status, prolonged length of stay, severe infection, and hospital costs were determined by univariate and multivariable regression analyses.

RESULTS

A total of 52,263 TSCI patients were identified, where 12,203 (23.3%) patients were frail. After adjusting for relevant confounders, frailty was independently associated with increased risk for in-hospital mortality [adjusted odds ratio (aOR) = 1.25, 95% CI:1.04-1.49], unfavorable discharge (aOR =1.15, 95% CI: 1.09-1.22), prolonged length of stay (aOR =1.32, 95% CI: 1.24-1.40), and severe infection (aOR =2.52, 95% CI: 2.24-2.83), but not hospital cost. Stratified analyses revealed frailty was associated with higher unfavorable discharge and severe infection regardless of age, Charlson Comorbidity Index, and injury level.

CONCLUSIONS

In acute TSCI, frailty is independently associated with increased risk for adverse inpatient outcomes in terms of in-hospital mortality, prolonged hospital stays, unfavorable discharge, and particularly severe infection.

Bacterial indole-3-lactic acid affects epithelium-macrophage crosstalk to regulate intestinal homeostasis

Tryptophan and its derivatives perform a variety of biological functions; however, the role and specific mechanism of many tryptophan derivatives in intestinal inflammation remain largely unclear. Here, we identified that an Escherichia coli strain (Ec-TMU) isolated from the feces of tinidazole-treated individuals, and indole-3-lactic acid (ILA) in its supernatant, decreased the susceptibility of mice to dextran sulfate sodium-induced colitis. Ec-TMU and ILA contribute to the relief of colitis by inhibiting the production of epithelial CCL2/7, thereby reducing the accumulation of inflammatory macrophages in vitro and in vivo. Mechanistically, ILA downregulates glycolysis, NF-κB, and HIF signaling pathways via the aryl hydrocarbon receptor, resulting in decreased CCL2/7 production in epithelial cells. Clinical evidence suggests that the fecal ILA level is negatively correlated with the progression indicator of inflammatory bowel diseases. These results demonstrate that ILA has the potential to regulate intestinal homeostasis by modulating epithelium-macrophage interactions.

Unintended placement of a double-J stent in the contralateral renal pelvis during laparoscopic pyeloplasty for pediatric hydronephrosis: a case report

BACKGROUND

The double-J stent (DJS) is a commonly used ureteral stent in urological surgeries, which provides support and drainage. However, the DJS may result in various complications such as infection, hematuria, stone formation, stent occlusion, and migration. Normally, one end of the DJS is located in the renal pelvis, and the other end in the bladder. In this case report, we describe the rare occurrence of a misplaced DJS during laparoscopic pyeloplasty, which was unintentionally placed in the contralateral renal pelvis.

CASE REPORT

A 4-month-old male infant was diagnosed with left hydronephrosis. After confirmation of the diagnosis, laparoscopic left pyeloplasty was performed with the placement of a DJS. The patient did not experience any discomfort, such as nausea, vomiting, refusal to feed, crying and restlessness, or fever, after the operation, and was discharged on postoperative day 4. The patient returned to the hospital for DJS removal 6 weeks after the operation. However, the kidneys, ureters, and bladder (KUB) X-ray examination showed that the DJS was unintentionally placed in the contralateral ureter and renal pelvis. The stent was confirmed and removed under cystoscopy. Postoperative examination of the DJS showed that there was a hole in the side of the middle of the stent for urine drainage, with no obstruction or contralateral hydronephrosis.

CONCLUSIONS

Misplacement of a DJS in the contralateral renal pelvis during laparoscopic pyeloplasty is a rare but potentially serious complication. Surgeons should be cautious when placing the stent and confirm its placement with imaging studies. Patients should be closely monitored for postoperative complications and prompt intervention should be taken if necessary.

The prognostic significance of KLRB1 and its further association with immune cells in breast cancer

Background

Killer cell lectin-like receptor B1 (KLRB1) is an important member of the natural killer cell gene family. This study explored the potential value of KLRB1 as a breast cancer (BC) biomarker and its close association with the tumor immune microenvironment during the development of BC.

Methods

We examined the differential expression of KLRB1 in pan-cancer. Clinical and RNA-Seq data from BC samples were evaluated in The Cancer Genome Atlas (TCGA) and validated in Gene Expression Omnibus (GEO) datasets and by immunohistochemistry (IHC) staining. The relationship between KLRB1 and clinical parameters was explored through Chi-square tests. The diagnostic value of KLRB1 was evaluated using a receiver operating characteristic (ROC) curve. Survival analysis was tested by Kaplan-Meier curves to demonstrate the relationship between KLRB1 and survival. Univariable and multivariate cox regression analyses were carried out as well. The analysis of immune infiltration level and gene set enrichment analysis (GSEA) were conducted to examine KLRB1's mechanism during the progression of BC. We used the Tumor Immune Estimation Resource (TIMER), the Cancer Single-cell Expression Map (CancerSCEM) database, the Tumor Immune Single-cell Hub (TISCH) database, and the Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) method to explore KLRB1's association with immune infiltration level and different quantitative distribution of immune cells. The relevant signaling pathways in BC associated with KLRB1 were identified using GSEA.

Results

The expression of KLRB1 was downregulated across the majority of cancers including BC. The lower KLRB1 expression group exhibited shorter relapse free survival (RFS) and overall survival (OS). IHC staining showed that KLRB1 staining was weaker in breast tumor tissues than in paratumors. Additionally, GSEA identified several pathway items distinctly enriched in BC. KLRB1 expression level was also positively related to the infiltrating number of immune cells in BC. Moreover, the CancerSCEM and TISCH databases as well as the CIBERSORT method demonstrated the close relationship between KLRB1 and immune cells, particularly macrophages.

Conclusion

Low KLRB1 expression was considered an independent prognostic biomarker and played an important role in the tumor immune microenvironment of BC patients.

Comprehensive analysis of 33 human cancers reveals clinical implications and immunotherapeutic value of the solute carrier family 35 member A2

Background

Solute carrier family 35 member A2 (SLC35A2), which belongs to the SLC35 solute carrier family of human nucleoside sugar transporters, has shown regulatory roles in various tumors and neoplasms. However, the function of SLC35A2 across human cancers remains to be systematically assessed. Insights into the prediction ability of SLC35A2 in clinical practice and immunotherapy response remains limited.

Materials and methods

We obtained the gene expression and protein levels of SLC35A2 in a variety of tumors from Molecular Taxonomy of Breast Cancer International Consortium, The Cancer Genome Atlas, Gene Expression Omnibus, Chinese Glioma Genome Atlas, and Human Protein Atlas databases. The SLC35A2 level was validated by immunohistochemistry. The predictive value for prognosis was evaluated by Kaplan-Meier survival and Cox regression analyses. Correlations between SLC35A2 expression and DNA methylation, genetic alterations, tumor mutation burden (TMB), microsatellite instability (MSI), and tumor microenvironment were performed using Spearman's correlation analysis. The possible downstream pathways of SLC35A2 in different human cancers were explored using gene set variation analysis. The potential role of SLC35A2 in the tumor immune microenvironment was evaluated via EPIC, CIBERSORT, MCP-counter, CIBERSORT-ABS, quanTIseq, TIMER, and xCell algorithms. The difference in the immunotherapeutic response of SLC35A2 under different expression conditions was evaluated by the tumor immune dysfunction and exclusion (TIDE) score as well as four independent immunotherapy cohorts, which includes patients with bladder urothelial carcinoma (BLCA, N = 299), non-small cell lung cancer (NSCLC, N = 72 and N = 36) and skin cutaneous melanoma (SKCM, N = 25). Potential drugs were identified using the CellMiner database and molecular docking.

Results

SLC35A2 exhibited abnormally high or low expression in 23 cancers and was significantly associated with the prognosis. In various cancers, SLC35A2 expression and mammalian target of rapamycin complex 1 signaling were positively correlated. Multiple algorithmic immune infiltration analyses suggested an inverse relation between SLC35A2 expression and infiltrating immune cells, which includes CD4+T cells, CD8+T cells, B cells, and natural killer cells (NK) in various tumors. Furthermore, SLC35A2 expression was significantly correlated with pan-cancer immune checkpoints, TMB, MSI, and TIDE genes. SLC35A2 showed significant predictive value for the immunotherapy response of patients with diverse cancers. Two drugs, vismodegib and abiraterone, were identified, and the free binding energy of cytochrome P17 with abiraterone was higher than that of SLC35A2 with abiraterone.

Conclusion

Our study revealed that SLC35A2 is upregulated in 20 types of cancer, including lung adenocarcinoma (LUAD), breast invasive carcinoma (BRCA), colon adenocarcinoma (COAD), and lung squamous cell carcinoma (LUSC). The upregulated SLC35A2 in five cancer types indicates a poor prognosis. Furthermore, there was a positive correlation between the overexpression of SLC35A2 and reduced lymphocyte infiltration in 13 cancer types, including BRCA and COAD. Based on data from several clinical trials, patients with LUAD, LUSC, SKCM, and BLCA who exhibited high SLC35A2 expression may experience improved immunotherapy response. Therefore, SLC35A2 could be considered a potential predictive biomarker for the prognosis and immunotherapy efficacy of various tumors. Our study provides a theoretical basis for further investigating its prognostic and therapeutic potentials.

Influencing factors of laparoscopic pelvic urethroplasty in the treatment of children with hydronephrosis

OBJECTIVE

The purpose of this study was to evaluate the clinical efficacy of laparoscopic pyeloureteroplasty in the treatment of children suffering from hydronephrosis.

PATIENTS AND METHODS

Our pediatric department received 160 children with hydronephrosis from January 2019 through December 2021. These children were randomly assigned to either the control group or the study group with 80 cases in each group. The control group underwent traditional open pyeloureteroplasty, while the study group underwent laparoscopic pyeloureteroplasty. After assessing the results of both groups, the clinical outcomes were compared.

RESULTS

The study group had a significantly shorter operating time, lower intraoperative bleeding rate, and shorter hospital stay than the control group. On the first day after the operation, there was no significant difference between the control and study groups, and on the seventh day after the operation, the study group's OPS was significantly lower than that of the control group. A significant difference was observed after treatment between the study group and the control group in terms of the anteroposterior diameter of the renal pelvis. Both groups' GFR increased significantly with time, and the GFR of the study group was significantly greater than that of the control group at 3 months after the operation, but there was no significant difference at 6 months after the operation. Postoperative adverse effects did not differ significantly between the two groups.

CONCLUSIONS

Pediatric laparoscopic pyeloureteroplasty can reduce intraoperative bleeding, shorten operation time and hospital stay, alleviate postoperative pain, and promote the recovery of postoperative renal morphology and function in children with hydronephrosis, which merits further discussion.

Efficacy of the modified Brisson+Devine procedure for the treatment of concealed penis

OBJECTIVE

This study was performed to evaluate the clinical efficacy of the modified Brisson+Devine procedure in the management of concealed penis.

PATIENTS AND METHODS

In this retrospective study, the medical data of 45 children diagnosed with concealed penis who underwent modified Brisson+Devine procedure in the Department of Urology of Anhui Provincial Children's Hospital between January 2019 and December 2021 were analyzed. Follow-up visits were performed at one, three, and six months postoperatively, and outcome measures included postoperative complications and parental satisfaction.

RESULTS

All 45 children completed the surgery uneventfully. At 3-4 days after surgery, the penile dressing and the urinary catheter were removed. The patients were discharged 4-5 days postoperatively without ischemic necrosis of metastatic flaps. The follow-up visits spanned from 7 to 33 months, with a mean of 14.6 months. A statistically significant increase in the penile length after surgery was observed (p<0.05). The postoperative penile appearance was good, and the parents of the children had high treatment satisfaction (p<0.05). 38 children developed postoperative transferred flap edema, and the edema disappeared at 3 months postoperatively.

CONCLUSIONS

The modified Brisson+ Devine procedure for concealed penis allows maximum use of the foreskin to improve the appearance of the penis and has a high safety profile by reducing postoperative complications, and provides high treatment satisfaction.

Adsorption of crystal violet on activated bamboo fiber powder from water: preparation, characterization, kinetics and isotherms

Biomass-activated carbon has made a great contribution as an adsorbent in the field of dye wastewater treatment. In this study, the response surface method (RSM) based on the Box-Behnken design was used to optimize the preparation process. Bamboo fiber activated carbon (BAC) with a specific surface area of 2892 m² g^-1 and a pore volume of 1.80 cm³ g^-1 was prepared. Various characterization methods (SEM, XPS, XRD, and Raman spectroscopy) were used to analyze the micro-structure of BAC. In the microscopic state, the BAC is fibrous and maintains the originally connected pores of the bamboo fiber. After high-temperature activation, the microcrystallinity of BAC decreases, and the degree of graphitization is low, indicating the presence of amorphous carbon. The adsorption capacity of BAC to crystal violet in simulated wastewater was evaluated via an adsorption experiment. Under the following conditions: the dosage of BAC was 0.04 g, the concentration was 600 mg L^-1, the adsorption temperature and time were 25 °C and 30 min, respectively, and the as-prepared BAC had a 99.96% removal rate. The adsorption process conformed to the pseudo-second-order kinetic model and Langmuir adsorption isotherm model, indicating that the adsorption process of CV on BAC belonged to monomolecular layer adsorption. The adsorption process occurs spontaneously and is accompanied by heat release, and the maximum adsorption capacity of BAC within a given concentration range could reach 1353.09 mg g^-1. SEM-EDS characterization before and after adsorption showed that ion exchange and the presence of oxygen-containing functional groups played an important role in promoting the adsorption process. The results show that BAC considerably affects CV removal, which has great application prospects.

Chemosensor with Ultra-High Fluorescence Enhancement for Assisting in Diagnosis and Resection of Ovarian Cancer

Fluorescence imaging-guided diagnostics is one of the most promising approaches for facile detection of tumors in situ owing to its simple operation and non-invasiveness. As a crucial biomarker for primary ovarian cancers, β-galactosidase (β-gal) has been demonstrated to be the significant molecular target for visualization of ovarian tumors. Herein, a membrane-permeable fluorescent chemosensor (namely, LAN-βgal) was synthesized for β-gal-specific detection using the d-galactose residue as a specific recognition unit and LAN-OH (Φ_F = 0.47) as a fluorophore. After β-gal was digested, the fluorescence of the initially quenched LAN-βgal (Φ_F < 0.001) was enhanced by up to more than 2000-fold, which exceeded the fluorescence enhancement of other previously reported probes. We also demonstrated that the chemosensor LAN-βgal could visualize endogenous β-gal and distinguish ovarian cancer cells from normal ovarian cells. Further, the chemosensor LAN-βgal was successfully applied to visualize the back tumor-bearing mouse model and peritoneal metastatic ovarian cancer model in vivo. More importantly, through in situ spraying, the proposed chemosensor was successfully employed to assist in the surgical resection of ovarian cancer tumors due to its high tumor-to-normal (T/N) tissue fluorescence ratio of 218. To the best of our knowledge, this is the highest T/N tissue fluorescence ratio ever reported. We believe that the LAN-βgal chemosensor can be utilized as a new tool for the clinical diagnosis and treatment of ovarian cancer.

Ratiometric detection and imaging of endogenous alkaline phosphatase activity by fluorescein-coumarin-based fluorescence probe

Alkaline phosphatase (ALP) is a type of enzyme that widely exists in various tissues of the human body; it plays an important role in regulating many cell functions. The development of a sensitive and accurate tool to detect the changes of ALP activity in organisms can contribute to research in the fields of biochemistry, cytology, clinical medicine, etc. In this paper, a small organic molecule-based ratiometric fluorescent probe (FCP) was designed based on the hydroxyl electron-donating group in fluorescein-coumarin protected by the phosphate group. ALP can trigger the fluorescence change through the enzyme-catalyzed cleavage of phosphoryl ester groups, and the ratio of ALP can be measured at wavelengths of 465 nm and 530 nm. The probe had high selectivity and sensitivity to ALP, and the detection limit measured under the optimal conditions in an aqueous medium reached 0.006 mU/mL. The ALP activity of human serum samples was determined using the probe and found to be in good agreement with that measured using commercial ALP kits. Finally, the probe was also successfully applied to image ALP in living hepatocytes with good selectivity and sensitivity.

Identification of RUNX1 and IFNGR2 as prognostic-related biomarkers correlated with immune infiltration and subtype differentiation of low-grade glioma

Immune cell infiltration occurs in the tumor microenvironment (TME) and influences cancer progression through interaction with tumor cells. Runt-related transcription factors (RUNXs), RUNX1-3, are the master regulators of development and differentiation and are all important to the development of immune cells. However, the role of RUNXs in the immune cells of TME remains unclear. In this study, we first used online related databases and related LGG data from TCGA and CGGA to conduct bioinformatics analysis, which confirmed that RUNXs were significantly and positively correlated with immune infiltration in multiple tumors, especially in low-grade glioma (LGG) and there was the highest correlation between RUNXs and the progress and prognosis of LGG. Furthermore, the functional enrichment analysis revealed that RUNXs might be involved in the inflammatory and immune responses of the biological processes, and RUNXs were tightly associated with the multiple immune checkpoint molecules. Subsequent results confirmed that RUNX1, as an independent prognostic factor for LGG, may target interferon-gamma receptor 2 (IFNGR2) to regulate glioma cell proliferation, invasion, and migration. Besides,we also found that the expression levels of RUNX1 and IFNGR2 were significantly reduced, and their correlation was enhanced in the IDH-mutant subtype. Patients with a high expression of RUNX1 and/or IFNGR2 (HH/H) in the IDH-mutant subtype showed poorer prognosis and significantly increased infiltration of M2 macrophages. This finding implied the possible key role of RUNX1 in the differentiation of IDH mutant subtypes as well as in the formation of tumor microenvironment (TME) infiltration signatures by monitoring IFNGR2.

Multifunctional Au Modified Ti3C2-MXene for Photothermal/Enzyme Dynamic/Immune Synergistic Therapy

Ti₃C₂-MXene-based composites provide multifunctional interfaces in diagnosis and treatment of tumors. Herein, we proposed a multifunctional nanoplatform based on Ti₃C₂-MXene-Au nanocomposites, which combines photothermal properties and peroxidase-like activity, accomplishing synergistic photothermal therapy (PTT) and enzyme dynamic therapy (EDT) accompanied by photoacoustic (PA) and thermal dual-mode imaging in vivo. Furthermore, PTT induces immunogenic cell death, and EDT promotes cell apoptosis, facilitating dendritic cell (DC) maturation and T cell infiltration into the tumor. On this basis, the antibody OX40 (αOX40) was utilized to further contribute immune therapy for reversing the immunosuppressive tumor microenvironment by activating CD4⁺ and CD8⁺ T cells. In summary, a triune of PTT/EDT/antitumor immune therapy is achieved by combining Ti₃C₂-MXene-Au nanocomposites and αOX40, which possesses several strong features of good biocompatibility, NIR-controlled targeting, significant cancer cell killing, and satisfactory biosafety in vitro and in vivo. Our work might highlight the promising application of MXene-based nanoplatforms for cancer therapy.

Disposable biosensor based on novel ternary Ru-PEI@PCN-333(Al) self-enhanced electrochemiluminescence system for on-site determination of caspase-3 activity

The number of death due to cancer-related diseases each year is at the alarming level and is constantly growing. Tools that can effectively and conveniently detect cancer cell apoptosis can play a significant role in cancer research, cancer therapy, and other related industries. Herein, we fabricated, for the first time, an ultrasensitive, disposable, self-enhanced off-on electrochemiluminescence (ECL) biosensor based on ternary Ru-PEI@PCN-333(Al) system to determine caspase-3 activity, the biomarker of apoptosis. The biosensor had a low detection limit of 0.017 pg/mL and was able to enhance the ECL emission and stability. A solid-state (SS) ECL strategy was adopted to overcome the relatively weak ECL emission due to the long distance between electrochemiluminophore and electrode surface. The analysis requires only one incubation step, which can significantly reduce the operational complexity and time. The biosensor had higher sensitivity, and the off-on ECL mode was achieved using caspase-3 as a switch. The on-site and rapid detection capability of the biosensor was achieved by the introduction of disposable screen-printed electrodes (SPEs). This study lays a foundation for the development of more advanced, ingenious, portable and reliable ECL devices for biosensing not only caspase-3, but also other bioanalytes.

Novel HLA-DRB1 alleles contribute risk for disease susceptibility in primary biliary cholangitis

BACKGROUND

Primary biliary cholangitis (PBC) is a complex disease with high heritability. We investigated the association between human leukocyte antigen (HLA)-DRB1 alleles and PBC in families and sporadic cases to evaluate the genetic components of the disease.

METHODS

We performed whole exome sequencing in three PBC families. We genotyped HLA-DRB1 and calculated the association between HLA-DRB1 alleles and the encoding amino acid sequences with the clinical features.

RESULTS

Ten variants harboured the HLA-DRB1 gene associated with PBC. DRB1×07:01, 14:01 and 14:05 were highly increased in PBC. Ten coding region polymorphisms were associated with PBC that encode the amino acid variants of HLA-DR β54, β59 and β66 located in the peptide-binding site of the MHC molecule. Glutamine at position 54 was confirmed as a risk amino acid, verifying the results of familial aggregation analysis of PBC families.

DISCUSSION

Familial aggregation analysis indicated that HLA-DRB1 is a candidate gene for the risk of disease course. Considering that amino acid variations are critical to peptide-binding properties, they underlie the major component of MHC association with PBC.

Giant modulation of optical nonlinearity by Floquet engineering

Strong periodic driving with light offers the potential to coherently manipulate the properties of quantum materials on ultrafast timescales. Recently, strategies have emerged to drastically alter electronic and magnetic properties by optically inducing non-trivial band topologies^1-6, emergent spin interactions^7-11 and even superconductivity¹². However, the prospects and methods of coherently engineering optical properties on demand are far less understood¹³. Here we demonstrate coherent control and giant modulation of optical nonlinearity in a van der Waals layered magnetic insulator, manganese phosphorus trisulfide (MnPS₃). By driving far off-resonance from the lowest on-site manganese d-d transition, we observe a coherent on-off switching of its optical second harmonic generation efficiency on the timescale of 100 femtoseconds with no measurable dissipation. At driving electric fields of the order of 10⁹ volts per metre, the on-off ratio exceeds 10, which is limited only by the sample damage threshold. Floquet theory calculations¹⁴ based on a single-ion model of MnPS₃ are able to reproduce the measured driving field amplitude and polarization dependence of the effect. Our approach can be applied to a broad range of insulating materials and could lead to dynamically designed nonlinear optical elements.

1334 Improving Patient Flow Through the Hand Trauma Pathway

Aim

A full-cycle audit was conducted at our plastic surgery unit, assessing adherence to hand trauma standards by the British Society for Surgery of the Hand. These stipulate that time from referral to clinic for open injuries and closed fractures should be within 24 hours and 72 hours respectively and time to theatre from date of injury (DOI) within 4 and 7 days, respectively.

Method

Data for the initial audit was collected from Nov 2019-Feb 2020 and for the re-audit from Aug-Dec 2020. Lists were generated of 50 patients with open injuries including flexor tendon, extensor tendon and nerve injuries and 50 hand fractures in both cycles. Data was collected on DOI, date of referral, clinic review and surgery.

Results

The initial audit results showed poor DOI documentation (open injuries 30%, fractures 54%). For open injuries, 44% met standards for clinical review within 24 hours and 94% for time to theatre. For fractures, 94% met the standard for time to clinic and 90% for time to theatre. The interventions included adding the standards to the clinic booking form and creating a mandatory DOI field on the referral system. The re-audit showed improvement of DOI documentation (open injuries 95%, fractures 100%) and the proportion of open injuries seen within 24 hours to 60%.

Conclusions

The interventions had a positive impact on our hand trauma pathway. Areas for improvement include reducing the number of patient visits to the service and encouraging early decision-making, particularly for patients reviewed in the emergency department.

Construction of direct Z-scheme Bi5O7I/UiO-66-NH2 heterojunction photocatalysts for enhanced degradation of ciprofloxacin: Mechanism insight, pathway analysis and toxicity evaluation

Direct Z-scheme Bi₅O₇I/UiO-66-NH₂ (denoted as BU-x) heterojunction photocatalysts were successfully constructed through ball-milling method. Photocatalytic activities of the as-prepared BU-x samples were determined by using a typical fluoroquinolone antibiotic, ciprofloxacin (CIP). All BU-x heterojunctions exhibited better CIP removal performances than that of pristine Bi₅O₇I and UiO-66-NH₂ upon exposure to white light irradiation. In comparison, the heterojunction with UiO-66-NH₂ content of 50 wt% (BU-5) showed excellent structural stability and the optimal adsorption-photodegradation efficiency for the CIP removal. The removal efficiency of CIP (10 mg/L) over BU-5 (0.75 g/L) achieved 96.1% within 120 min illumination. Meanwhile, the effect of photocatalyst dosage, pH and inorganic anions were systemically explored. Reactive species trapping experiments, electron spin resonance (ESR) signals, Mott-Schottky measurements and density functional theory (DFT) simulation revealed that the photo-generated holes (h⁺), hydroxyl radical (·OH) and superoxide radical (·O₂^-) played crucial roles in CIP degradation. This result can be ascribed to that the unique Z-scheme charge transfer configuration retained the excellent redox capacities of Bi₅O₇I and UiO-66-NH₂. Meanwhile, the CIP degradation pathways and the toxicity of various intermediates were subsequently analyzed. This work provided a feasible idea for removing antibiotics by bismuth-rich bismuth oxyhalide/MOF-based heterostructured photocatalysts.

Liquid repellency enabled antipathogen coatings

Currently, Coronavirus Disease 2019 (COVID-19)-a respiratory contagion spreading through expiratory droplets-has evolved into a global pandemic, severely impacting the public health. Importantly, the emerging of immune evasion SARS-CoV-2 variants and the limited effect of current antivirals against SARS-CoV-2 in clinical trials suggested that alternative strategies in addition to the conventional vaccines and antivirals are required to successfully control the COVID-19 pandemic. Here, we propose to use liquid-repellent coatings to prevent the spread of the disease in the absence of effective vaccines, antimicrobial agents, or therapeutics, wherein the deposition and penetration of pathogen droplets are prohibited. We use SARS-CoV-2 as a model pathogen and find that SARS-CoV-2 remnants are reduced by seven orders of magnitude on coated surfaces, yielding a repelling efficacy far outperforming the inactivation rate of disinfectants. The SARS-CoV-2 remnant scales exponentially with the liquid/solid adhesion, uncovering the mechanism and effective means for minimizing pathogen attachment. The antipathogen coating that both repels and inactivates pathogens is demonstrated by incorporating the super-liquid-repellent coating with antipathogen additives. Together with its versatility over a wide range of substrates and pathogens, the novel antipathogen coating is of considerable value for infection control in everyday life as well as during pandemics.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Constraints on Cosmic Strings Using Data from the Third Advanced LIGO-Virgo Observing Run

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO-Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10^{-15}. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

Reducing pain through distraction therapy in small acute paediatric burns

INTRODUCTION

The majority of patients who sustained small (low % total body surface area [TBSA]) burns are assessed in an outpatient setting. This can be a traumatic experience, particularly, for paediatric patients. During the initial assessment pharmacological and non-pharmacological adjuncts, such as distraction therapy, can be employed to provide an environment that may reduce and minimise distress. In this study, we investigated whether distraction therapy reduces objective pain scores during the outpatient assessment of small acute burns in children.

METHODS

Two cohorts of patients were formed. In the first group (group A), the children received analgesia and routine nursing care. In the second group (group B), the children received specialist distraction therapy in addition to the same analgesia and nursing care. We recorded patient demographics, TBSA, anatomical sites and mechanism of burn. The Wong Baker™ visual analogue scale (VAS) was used to convert perceived pain, as reported by the patient or parent, into a numerical value at three set intervals during the consultation.

RESULTS

50 patients were recruited with 32 patients in group A and 18 in group B. A larger TBSA positively correlated with higher pain scores (p < 0.05). At the start of the consultation the mean pain score without distraction therapy was 1.55 and with specialist distraction therapy was 0.33 (p < 0.05). The mean peak pain score during dressing change without distraction therapy was 6.80 and with specialist distraction was 4.47 (p < 0.05). At the end of the procedure, the mean pain score was 2.12 without distraction therapy and with specialist distraction 1.75.

CONCLUSION

This study of pain scores in small acute paediatric burns has shown that distraction therapy provided by a qualified play specialist can reduce maximal pain by over 2 points on the Wong-Baker™ VAS. Consideration should be given to ensure that distraction therapy is available at all times during initial consultations for children who have sustained small burns.

Early mandated social distancing is a strong predictor of reduction in peak daily new COVID-19 cases

OBJECTIVES

Mandated social distancing has been applied globally to reduce the spread of coronavirus disease 2019 (COVID-19). However, the beneficial effects of this community-based intervention have not been proven or quantified for the COVID-19 pandemic.

STUDY DESIGN

This is a regional population-level observational study.

METHODS

Using publicly available data, we examined the effect of timing of mandated social distancing on the rate of COVID-19 cases in 119 geographic regions, derived from 41 states within the United States and 78 other countries. The highest number of new COVID-19 cases per day recorded within a geographic unit was the primary outcome. The total number of COVID-19 cases in regions where case numbers had reached the tail end of the outbreak was an exploratory outcome.

RESULTS

We found that the highest number of new COVID-19 cases per day per million persons was significantly associated with the total number of COVID-19 cases per million persons on the day before mandated social distancing (β = 0.66, P < 0.0001). These findings suggest that if mandated social distancing is not initiated until the number of existing COVID-19 cases has doubled, the eventual peak would result in 58% more COVID-19 cases per day. Subgroup analysis on those regions where the highest number of new COVID-19 cases per day has peaked showed increase in β values to 0.85 (P < 0.0001). The total number of cases during the outbreak in a region was strongly predicted by the total number of COVID-19 cases on the day before mandated social distancing (β = 0.97, P < 0.0001).

CONCLUSIONS

Initiating mandated social distancing when the numbers of COVID-19 cases are low within a region significantly reduces the number of new daily COVID-19 cases and perhaps also reduces the total number of cases in the region.

Lower-Limb Sensorimotor Deprivation-Related Brain Activation in Patients With Chronic Complete Spinal Cord Injury

This study aims to investigate functional brain reorganization brought about by the loss of physical movement and sensory feedback in lower limbs in chronic spinal cord injury (SCI). Eleven paraplegia patients with SCI and 13 healthy controls (HCs) were recruited. The experimental task used was a visuomotor imagery task requiring subjects to engage in visualization of repetitive tapping movements of the upper or lower limbs. Blood oxygen level-dependent (BOLD) responses were captured during the experimental task, along with the accuracy rate and the response time. The SCI patients performed worse in the Rey Auditory Verbal Learning Test (RAVLT) and the Trail Making Test. SCI patients had a larger BOLD signal in the left lingual gyrus and right external globus pallidus (GPe) when imagining lower-limb movements. For the upper-limb task, SCI patients showed stronger BOLD responses than the HCs in extensive areas over the brain, including the bilateral precentral gyrus (preCG), bilateral inferior parietal gyrus, right GPe, right thalamus, left postcentral gyrus, and right superior temporal gyrus. In contrast, the HCs displayed stronger BOLD responses in the medial frontal gyrus and anterior cingulate gyrus for both upper- and lower-limb tasks than the SCI patients. In the SCI group, for the upper-limb condition, the amplitudes of BOLD responses in the left preCG were negatively correlated with the time since injury (r = -0.72, p = 0.012). For the lower-limb condition, the amplitudes of BOLD responses in the left lingual gyrus were negatively correlated with the scores on the Short Delay task of the RAVLT (r = -0.73, p = 0.011). Our study provided imaging evidence for abnormal changes in brain function and worsened cognitive test performance in SCI patients. These findings suggested possible compensatory strategies adopted by the SCI patients for the loss of sensorimotor function from the lower limbs when performing a limb imagery task.

Factors affecting stability and infectivity of SARS-CoV-2

BACKGROUND

In late 2019, a novel human coronavirus - severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) - emerged in Wuhan, China. This virus has caused a global pandemic involving more than 200 countries. SARS-CoV-2 is highly adapted to humans and readily transmits from person-to-person.

AIM

To investigate the infectivity of SARS-CoV-2 under various environmental and pH conditions. The efficacies of various laboratory virus inactivation methods and home disinfectants against SARS-CoV-2 were investigated.

METHODS

The residual virus in dried form or in solution was titrated on to Vero E6 cells on days 0, 1, 3, 5 and 7 after incubation at different temperatures. Viral viability was determined after treatment with various disinfectants and pH solutions at room temperature (20-25^oC).

FINDINGS

SARS-CoV-2 was able to retain viability for 3-5 days in dried form or 7 days in solution at room temperature. SARS-CoV-2 could be detected under a wide range of pH conditions from pH 4 to pH 11 for several days, and for 1-2 days in stool at room temperature but lost 5 logs of infectivity. A variety of commonly used disinfectants and laboratory inactivation procedures were found to reduce viral viability effectively.

CONCLUSION

This study demonstrated the stability of SARS-CoV-2 on environmental surfaces, and raises the possibility of faecal-oral transmission. Commonly used fixatives, nucleic acid extraction methods and heat inactivation were found to reduce viral infectivity significantly, which could ensure hospital and laboratory safety during the SARS-CoV-2 pandemic.

0388 Predictors of Incident Reduced Sleep Efficiency in Community-Dwelling Older Women

Introduction

There is a paucity of longitudinal studies with sleep efficiency (SE) as an outcome measure. Our objective was to examine potential risk factors for incident reduced SE among community-dwelling women in late life.

Methods

We studied 700 women (mean age 82.5 [SD=3.0] years) with a SE ≥70% at the Year 16 (2002-04) visit of the Study of Osteoporotic Fractures with a follow-up measure of SE at the Year 20 (2006-08) visit. SE (percentage of time sleeping while in bed) at both visits was measured using a wrist actigraph with data collected for an average of four 24-hour periods. Women were classified as having incident reduced SE if they had SE &lt;70% at Year 20. Logistic regression was used to estimate the associations between potential risk factors (demographics, lifestyle, use of medications, self-reported medical conditions, functional impairment, frailty, mental and physical health) at Year 16 and reduced SE at Year 20. The association of each candidate risk factor with reduced SE at Year 20 was examined in models adjusted for age, clinical site and continuous SE at Year 16. Candidate risk factors with Benjamin Hochberg false-discovery rate q-values &lt;0.10 were included in a final multivariate model.

Results

Among the 700 eligible women, 62 (8.9%) developed incident reduced SE between the Year 16 and Year 20 visits. After adjusting for age, site and baseline SE, antidepressant use [OR=3.06; 95% CI: 1.50-6.25], benzodiazepine use [OR=2.97; 95% CI: 1.30-6.80] and the presence of hypertension [OR=2.83; 95% CI: 1.47-5.45] at Year 16 were independently associated with a higher odds of having reduced SE at follow-up.

Conclusion

These findings suggest that antidepressant use, benzodiazepine use and hypertension are risk factors or markers for the development of reduced sleep efficiency in older women. Future studies are warranted to examine the underlying mechanisms for these associations.

Support

The Study of Osteoporotic Fractures (SOF) is supported by National Institutes of Health funding. The National Institute on Aging (NIA) provides support under the following grant numbers: R01 AG005407, R01 AR35582, R01 AR35583, R01 AR35584, R01 AG005394, R01 AG027574, and R01 AG027576.

Clinical application of flap or flapless buccal surgery on the extractions of mesially/horizontally impacted 3rd molar with high or medium position impact: A comparative study

PURPOSE

To investigate and compare the clinical application of flap or flapless buccal surgery on the extractions of mesially/horizontally impacted 3rd molar with high or medium position impact in terms of the average surgery duration, number of root fracture, postoperative pain degree and duration, postoperative swelling degree and duration, degree of limitation of mouth opening.

MATERIALS AND METHODS

The present study was conducted of 28 patients who were examined and underwent bilateral extraction of impacted mandibular 3rd molar. One molar was randomly extracted with flap buccal surgery (Control Group, CG) and the other one with flapless buccal surgery (Experimental Group, EG) in the same patient.

RESULTS

Gender distribution, average age, average surgery duration and number of root fracture between the two groups were not statistically significant (P>0.05). The postoperative pain degree, swelling degree and degree of limitation of mouth opening were all significantly greater in CG than EG. Moreover, the duration of postoperative pain and swelling were all were all significantly longer in CG than EG (0.01<P<0.05).

CONCLUSION

Compared with the flap buccal surgery on the extractions of mesially/horizontally impacted 3rd molar with high or medium position impact, the clinical use of the flapless buccal surgery is a safe and effective method with less swelling, pain and degree of limitation of mouth opening. However, we need further study based on the broader indications, a much larger number of patients included and a follow-up in the longer term to confirm our point.

[Correlation between the changes of innate lymphoid cells in peripheral blood of systemic lupus erythematosus and its clinical significance]

Objective: To explore the function and role of innate lymphoid cells in the pathogenesis of systemic lupus erythematosus (SLE) at different disease activity levels. Methods: From Nov 2017 to May 2018, 40 patients with SLE and 15 age-matched healthy non-immune-related diseases controls were enrolled from Anhui provincial hospital. According to the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI)-2K, the patients were divided into active group (n=20) and remission group (n=20). The frequency of ILCs, B cells, CD4+T and CD8+T cells from peripheral blood mononuclear cells (PBMCs) was detected by flow cytometry. The subsets of ILCs in each group were compared with the subsets of B cells and T cell respectively. The levels of IL-4, IL-33 and IFN-γ in each group were tested by ELISA. Result: Compared with the control group, ILC1 percentage was significantly increased in SLE active group [(22.33%±2.52%) vs (14.56%±1.28%), P=0.018 1]; ILC2 percentage was decreased significantly in both remission group [(19.67%±1.83%) vs (42.48%±3.46%), P<0.000 1] and active group [(8.67%±0.83%) vs (19.67%±1.83%), P<0.000 1]; ILC3 percentage was decreased significantly in active group [(5.72%±1.08%) vs (14.35%±2.40%), P=0.001 3]. SLEDAI score was negatively correlated with the percentage of ILC2 (P=0.023 9) in all patients. The percentage of ILCs in the remission group (P=0.046 2) and activity group (P=0.003 7) were both increased significantly. Moreover, the percentage of ILC2 in active group was negatively correlated with CD4+T cells (P=0.030 8), and the serum IgG was negatively correlated with ILC2% in all patients (P=0.013 8). Compared with control group or remission group, the levels of IFN-γ (F=10.91, P=0.000 1) and IL-4 (F=6.046, P=0.004 7) in active group were remarkable higher. However, IL-33 was significantly reduced in active group (F=6.645, P=0.002 7). The percentage of ILC2 (r=0.154 3, P=0.028 8) and ILC3 (r=0.313 6, P=0.001 1) in all patients with SLE were positively correlated with the level of IL-4. Conclusion: The percentage of ILCs is related to disease activity, and ILCs play a "double-edged" role in the pathogenesis of SLE. Its function and mechanism are worth further exploration.

Allergen-specific immunotherapy induces regulatory T cells in an atopic dermatitis mouse model

BACKGROUND

Several studies have demonstrated that allergen-specific immunotherapy (SIT) can be an effective treatment for atopic dermatitis (AD). However, there is no relevant mouse model to investigate the mechanism and validate the novel modality of SIT in AD.

METHODS

NC/Nga mice with induced AD-like skin lesions received a subcutaneous injection of SIT (an extract of the house dust mite Dermatophagoides farinae [DfE]) or placebo for 5 weeks). Clinical and histological improvements of AD-like skin lesions were examined. The responses of local and systemic regulatory T (Treg) cells, natural killer (NK) cells, B cells, serum immunoglobulin, and T-cell cytokine response to DfE were evaluated to determine the underlying mechanism of the observed results.

RESULTS

Specific immunotherapy significantly improved AD-like skin lesions. Histologically, SIT decreased epidermal thickness and reduced inflammatory cell infiltration, especially that of eosinophils. Concomitantly, SIT suppressed Th2 responses and induced local infiltration of Treg cells into the skin. Also, SIT induced the immunoglobulin G4 and attenuated allergen-specific immunoglobulin E. Furthermore, SIT induced local and systemic IL-10-producing Treg cells and regulatory NK cells.

CONCLUSION

We established a SIT model on AD mice and showed that our model correlates well with previous reports about SIT-treated patients. Also, we revealed NK cells as another possible resource of IL-10 in SIT. Based on our results, we suggest our SIT model as a useful tool to investigate mechanism of action of SIT and to validate the efficacy of new SIT modalities for the treatment of AD.

Pinewood nematode infection alters root mycoflora of Pinus tabulaeformis Carr

AIMS

This study investigates pinewood nematode's impacts on root mycoflora of Pinus tabulaeformis.

METHODS AND RESULTS

The biomass, colonization rate, community structure and diversity of root-associated fungi were investigated in pinewood nematode-infected and nematode-noninfected P. tabulaeformis. The results indicated that the roots of P. tabulaeformis were colonized highly by root-associated fungi, mainly ectomycorrhizal fungi (ECMF) and dark septate endophytes. Infection of pinewood nematode was associated with a significant (P < 0·05) decrease in root colonization rates by ECMF, dark septate endophytes and total hyphae, as well as in fungal biomass in the roots. Illumina MiSeq sequences of tagged amplicons of 18S rDNA region revealed Basidiomycota (65·70%) and Ascomycota (34·14%) as the dominant root-associated fungi in roots of P. tabulaeformis. Among the detected operational taxonomic units (OTUs), ECMF and dark septate endophytes exhibited a higher relative abundance in trees infected by pinewood nematode compared with noninfected ones.

CONCLUSIONS

The infection of pinewood nematode altered the composition and OTU abundance of root-associated fungi community in P. tabulaeformis roots with a decrease in the biomass, species richness and diversity of root-associated fungi, as well as in the colonization rates and abundance of ECMF and dark septate endophytes.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is an important contribution for better understanding the interaction between pine wilt disease and root-associated fungi.

Evidence of an Improper Displacive Phase Transition in Cd_{2}Re_{2}O_{7} via Time-Resolved Coherent Phonon Spectroscopy

We have used a combination of ultrafast coherent phonon spectroscopy, ultrafast thermometry, and time-dependent Landau theory to study the inversion symmetry breaking phase transition at T_{c}=200  K in the strongly spin-orbit coupled correlated metal Cd_{2}Re_{2}O_{7}. We establish that the structural distortion at T_{c} is a secondary effect through the absence of any softening of its associated phonon mode, which supports a purely electronically driven mechanism. However, the phonon lifetime exhibits an anomalously strong temperature dependence that decreases linearly to zero near T_{c}. We show that this behavior naturally explains the spurious appearance of phonon softening in previous Raman spectroscopy experiments and should be a prevalent feature of correlated electron systems with linearly coupled order parameters.