High-Efficiency Circularly Polarized Light-Emitting Diodes Based on Chiral Metal Nanoclusters.

Circularly polarized light-emitting diodes (CP-LEDs) are critical for next-generation optical technologies, ranging from holography to quantum information processing. Currently deployed chiral luminescent materials, with their intricate synthesis and processing and limited efficiency, are the main bottleneck for CP-LEDs. Chiral metal nanoclusters (MNCs) are potential CP-LED materials, given their ease of synthesis and processability as well as diverse structures and excited states. However, their films are usually plagued by inferior electronic quality and aggregation-caused photoluminescence quenching, necessitating their incorporation into host materials; without such a scheme, MNC-based LEDs exhibit external quantum efficiencies (EQEs) < 10%. Herein, we achieve an efficiency leap for both CP-LEDs and cluster-based LEDs by using novel chiral MNCs with aggregation-induced emission enhancement. CP-LEDs using enantiopure MNC films attain EQEs of up to 23.5%. Furthermore, by incorporating host materials, the devices yield record EQEs of up to 36.5% for both CP-LEDs and cluster-based LEDs, along with electroluminescence dissymmetry factors (|gEL|) of around 1.0 × 10-3. These findings open a new avenue for advancing chiral light sources for next-generation optoelectronics.

Phase Engineering Reinforced Energy Transfer for High-Performance Blue Perovskite Light-Emitting Diodes.

Layered metal-halide perovskites, a category of self-assembled quantum wells, are of paramount importance in emerging photonic sources, such as lasers and light-emitting diodes (LEDs). Despite high trap density in two-dimensional (2D) perovskites, efficient non-radiative energy funneling from wide- to narrow-bandgap components, sustained by the Förster resonance energy transfer (FRET) mechanism, contributes to efficient luminescence by light or electrical injection. Herein, it is demonstrated that bandgap extension of layered perovskites to the blue-emitting regime will cause sluggish and inefficient FRET, stemming from the tiny spectral overlap between different phases. Motivated by the importance of blue LEDs and inefficient energy transfer in materials with phase polydispersity, wide-bandgap quasi-2D perovskites with narrow phase distribution, improved crystallinity, and the pure crystal orientation perpendicular to the charge transport layer are developed. Based on this emitter, high-performance blue perovskite LEDs with improved electroluminescence (EL) external quantum efficiency (EQE) of 7.9% at 478 nm, a narrow full width at half-maximum (FWHM) of 22 nm and a more stable EL spectra are achieved. These results provide an important insight into spectrally stable and efficient blue emitters and EL devices based on perovskites.

Perovskite light-emitting diodes with external quantum efficiency exceeding 20 per cent.

Metal halide perovskite materials are an emerging class of solution-processable semiconductors with considerable potential for use in optoelectronic devices1-3. For example, light-emitting diodes (LEDs) based on these materials could see application in flat-panel displays and solid-state lighting, owing to their potential to be made at low cost via facile solution processing, and could provide tunable colours and narrow emission line widths at high photoluminescence quantum yields4-8. However, the highest reported external quantum efficiencies of green- and red-light-emitting perovskite LEDs are around 14 per cent7,9 and 12 per cent8, respectively-still well behind the performance of organic LEDs10-12 and inorganic quantum dot LEDs13. Here we describe visible-light-emitting perovskite LEDs that surpass the quantum efficiency milestone of 20 per cent. This achievement stems from a new strategy for managing the compositional distribution in the device-an approach that simultaneously provides high luminescence and balanced charge injection. Specifically, we mixed a presynthesized CsPbBr3 perovskite with a MABr additive (where MA is CH3NH3), the differing solubilities of which yield sequential crystallization into a CsPbBr3/MABr quasi-core/shell structure. The MABr shell passivates the nonradiative defects that would otherwise be present in CsPbBr3 crystals, boosting the photoluminescence quantum efficiency, while the MABr capping layer enables balanced charge injection. The resulting 20.3 per cent external quantum efficiency represents a substantial step towards the practical application of perovskite LEDs in lighting and display.

Efficient Perovskite Light-Emitting Diodes with Chemically Bonded Contact and Regulated Charge Behavior.

Efficient charge injection and radiative recombination are essential to achieving high-performance perovskite light-emitting diodes (Pero-LEDs). However, the perovskite emission layer (EML) and the electron transport layer (ETL) form a poor physically interfacial contact and non-negligible charge injection barrier, limiting the device performance. Herein, we utilize a phosphine oxide, 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T), to treat the perovskite/ETL interface and form a chemically bonded contact. Specifically, PO-T2T firmly bonds on the perovskite's surface and grain boundaries through a dative bond, effectively passivating the uncoordinated lead defects. Additionally, PO-T2T has high electron mobility and establishes an electron transport highway to bridge the ETL and EML. As a result, a maximum external quantum efficiency (EQEmax) of 22.06% (average EQEmax of 20.02 ± 1.00%) and maximum luminance (Lmax) of 103286 cd m-2 have been achieved for the champion device. Our results indicate that EML/ETL interface modifications are crucial for the fabrication of highly efficient Pero-LEDs.

Atomic-Scale Polarization and Strain at the Surface of Lead Halide Perovskite Nanocrystals.

Inorganic halide perovskite nanocrystals (NCs) are being widely explored as next-generation optoelectronic materials. Critical to understanding the optoelectronic properties and stability behavior of perovskite NCs is the material's surface structure, where the local atomic configuration deviates from that of the bulk. Through low-dose aberration-corrected scanning transmission electron microscopy and quantitative imaging analysis techniques, we directly observed the atomic structure at the surface of the CsPbBr3 NCs. CsPbBr3 NCs are terminated by a Cs-Br plane, and the surface Cs-Cs bond length decreases significantly (∼5.6%) relative to the bulk, imposing compressive strain and inducing polarization, which we also observed in CsPbI3 NCs. Density functional theory calculations suggest such a reconstructed surface contributes to the separation of holes and electrons. These findings enhance our fundamental understanding of the atomic-scale structure, strain, and polarity at the surface of inorganic halide perovskites and provide valuable insights into designing stable and efficient optoelectronic devices.

Conductive Phosphine Oxide Passivator Enables Efficient Perovskite Light-Emitting Diodes.

Recently, surface passivation has been proved to be an essential approach for obtaining efficient and stable perovskite light-emitting diodes (Pero-LEDs). Phosphine oxides performed well as passivators in many reports. However, the most commonly used phosphine oxides are insulators, which may inhibit carrier transport between the perovskite emitter and charge-transporter layers, limiting the corresponding device performance. Here, 2,7-bis(diphenylphosphoryl)-9,9'-spirobifluorene (SPPO13), a conductive molecule with two phosphine oxide functional groups, is introduced to modify the perovskite emitting layer. The bifunctional SPPO13 can passivate the nonradiative defects of perovskite and promote electron injection at the interface of perovskite emitter and electron-transporter layers. As a result, the corresponding Pero-LEDs obtain a maximum external quantum efficiency (EQE) of 22.3%. In addition, the Pero-LEDs achieve extremely high brightness with a maximum of around 190 000 cd/m2.

A Dual-Mode Optical Thermometer with High Sensitivity Based on BaAl12O19:Sm2+/SrAl12O19:Sm3+ Solid Solution Phosphors.

A series of BaAl12O19:Sm2+/SrAl12O19:Sm3+ mixed-phase phosphors were produced in one step using the traditional high-temperature solid-phase process. Because Sm is divalent in BaAl12O19 and trivalent in SrAl12O19, the coexistence of Sm2+ and Sm3+ is realized in the mixed-phase host. Since the temperature sensitivity of Sm2+ and Sm3+ in the solid solution host is significantly different, this makes it possible for the sample to measure temperature based on the fluorescence intensity ratio (FIR). The crystal model, ion emission spectrum, and temperature sensitivity of these phosphors are studied in detail. Under the co-excitation of a 410 nm excitation source, this sample has excellent temperature measurement performance in the range of 313-513 K. Based on the FIR method, the maximum absolute temperature sensitivity (Sa) is 0.55 K-1 at 513 K, and the maximum relative temperature sensitivity (Sr) is 2.47%K-1 at 453 K. Moreover, based on the photoluminescence lifetime temperature measurement mode, the largest value of Sa at 413 K is 0.046 K-1, and the maximum value of Sr at 473 K is 3.10%K-1. In short, the BaAl12O19:Sm2+/SrAl12O19:Sm3+ solid solution is a kind of phosphor with nice temperature measurement ability, and it has very strong potential in the application of noncontact optical thermometers.

Risk factors for 30-day mortality in patients with head and neck cancer bleeding in the emergency department.

BACKGROUND: Acute head and neck cancer (HNC) bleeding is a life-threatening situation that frequently presents to the emergency department (ED). The purpose of the present study was to analyze the risk factors for the 30-day mortality in patients with HNC bleeding. METHODS: We included patients who presented to the ED with HNC bleeding (n = 241). Patients were divided into the survivor and nonsurvivor groups. Variables were compared, and the associated factors were examined with Cox's proportional hazard model. RESULTS: Of the 241 patients enrolled, the most common bleeding site was the oral cavity (n = 101, 41.9%). More than half of the patients had advanced HNC stage while 41.5% had local recurrence. The proportion of active bleeding was significantly higher in the nonsurvivor group (70.5% vs. 53.3%, p = 0.038). 42.3% received blood transfusion and 5.0% required inotropic support. In total, 21.2% of the patients experienced rebleeding, and 18.3% died within 30 days. Multivariate analyses indicated that a heart rate > 100 (beats/min) (HR = 2.42; Cl 1.15-5.06; p = 0.019) and inotropic support (HR = 3.00; Cl 1.14-7.89; p = 0.026) were statistically significant independent risk factors for 30-day mortality. CONCLUSIONS: The results of this study may aid physicians in the evaluation of short-term survival in HNC bleeding patients and provide critical information for risk stratification and medical decisions.

Clinical Characteristics and In-Hospital Outcomes in Dialysis Patients with Septic Arthritis.

Background and Objectives: Septic arthritis is a medical emergency associated with high morbidity and mortality. The incidence rate of septic arthritis among dialysis patients is higher than the general population, and dialysis patients with bacteremia frequently experience adverse outcomes. The aim of this study was to identify the clinical features and risk factors for longer hospital length of stay (LOS), positive blood culture, and in-hospital mortality in dialysis patients with septic arthritis. Materials and Methods: The medical records of 52 septic arthritis dialysis patients admitted to our hospital from 1 January 2009 to 31 December 2020 were analyzed. The primary outcomes were bacteremia and in-hospital mortality. Variables were compared, and risk factors were evaluated using linear and logistic regression models. Results: Twelve (23.1%) patients had positive blood cultures. A tunneled cuffed catheter for dialysis access was used in eight (15.4%) patients, and its usage rate was significantly higher in patients with positive blood culture than in those with negative blood culture (41.7 vs. 7.5%, p = 0.011). Fever was present in 15 (28.8%) patients, and was significantly more frequent in patients with positive blood culture (58.3 vs. 20%, p = 0.025). The most frequently involved site was the hip (n = 21, 40.4%). The most common causative pathogen was Gram-positive cocci, with MRSA (n = 7, 58.3%) being dominant. The mean LOS was 29.9 ± 25.1 days. The tunneled cuffed catheter was a significant predictor of longer LOS (Coef = 0.49; Cl 0.25−0.74; p < 0.001). The predictors of positive blood culture were fever (OR = 4.91; Cl 1.10−21.83; p = 0.037) and tunneled cuffed catheter (OR = 7.60; Cl 1.31−44.02; p = 0.024). The predictor of mortality was tunneled cuffed catheter (OR = 14.33; Cl 1.12−183.18; p = 0.041). Conclusions: In the dialysis population, patients with tunneled cuffed catheter for dialysis access had a significantly longer hospital LOS. Tunneled cuffed catheter and fever were independent predictors of positive blood culture, and tunneled cuffed catheter was the predictor of in-hospital mortality. The recognition of the associated factors allows for risk stratification and determination of the optimal treatment plan in dialysis patients with septic arthritis.

N-acetylcysteine and ascorbic acid therapy for acute hepatic injury after hexavalent chromium ingestion.

WHAT IS KNOWN AND OBJECTIVE: Hexavalent (VI) chromium is a powerful oxidant that can produce cellular oxidative stress and multi-organ system dysfunction. The role of antioxidants such as N-acetylcysteine (NAC) and ascorbic acid in alleviating organ damage in humans remains unclear. CASE DESCRIPTION: We present a 47-year-old male who ingested 30 mL of plating solution and developed hepatic injury. He was treated with NAC and ascorbic acid with improvement in hepatic function. However, his clinical conditions and jaundice worsened again after discontinuing these therapies. WHAT IS NEW AND CONCLUSION: Our findings suggest a potential role for antioxidant therapy for acute hexavalent chromium poisoning.

Efficient and Stable Low-Bandgap Perovskite Solar Cells Enabled by a CsPbBr3-Cluster Assisted Bottom-up Crystallization Approach.

Recently, low-bandgap formamidinium lead iodide FAPbI3-based perovskites are of particular interest for high-performance perovskite solar cells (PSCs) due to their broad spectral response and high photocurrent output. However, to inhibit the spontaneous α-to-δ phase transition, 15-17% (molar ratio) of bromide and cesium or methylammonium incorporated into the FAPbI3 are indispensable to achieve efficient PSCs. In return, the high bromide content will increase bandgap and narrow the spectral response region. If simply reducing the bromide content, the corresponding PSCs exhibit inferior operational stability due to α-to-δ phase transition, interface degradation, and halide migration. Herein, we report a CsPbBr3-cluster assisted vertically bottom-up crystallization approach to fabricate low-bromide (1% ∼ 6%), α-phase pure, and MA-free FAPbI3-based PSCs. The clusters, in the size of several nanometers, could act as nuclei to facilitate vertical growth of high quality α-FAPbI3 perovskite crystals. Moreover, these clusters can show further intake by perovskite after thermal annealing, which improves the phase homogeneity of the as-prepared perovskite films. As a result, the corresponding mesoporous PSCs deliver a champion efficiency of 21.78% with photoresponse extended to 830 nm. Moreover, these devices show remarkably improved operational stability, retaining ∼82% of the initial efficiency after 1,000 h of maximum power point tracking under 1 sun condition.

Characterizing the proton loading site in cytochrome c oxidase.

Cytochrome c oxidase (CcO) uses the energy released by reduction of O2 to H2O to drive eight charges from the high pH to low pH side of the membrane, increasing the electrochemical gradient. Four electrons and protons are used for chemistry, while four more protons are pumped. Proton pumping requires that residues on a pathway change proton affinity through the reaction cycle to load and then release protons. The protonation states of all residues in CcO are determined in MultiConformational Continuum Electrostatics simulations with the protonation and redox states of heme a, a3, Cu(B), Y288, and E286 used to define the catalytic cycle. One proton is found to be loaded and released from residues identified as the proton loading site (PLS) on the P-side of the protein in each of the four CcO redox states. Thus, the same proton pumping mechanism can be used each time CcO is reduced. Calculations with structures of Rhodobacter sphaeroides, Paracoccus denitrificans, and bovine CcO derived by crystallography and molecular dynamics show the PLS functions similarly in different CcO species. The PLS is a cluster rather than a single residue, as different structures show 1-4 residues load and release protons. However, the proton affinity of the heme a3 propionic acids primarily determines the number of protons loaded into the PLS; if their proton affinity is too low, less than one proton is loaded.

Concurrent chemoradiotherapy plus adjuvant chemotherapy versus concurrent chemoradiotherapy in locoregionally advanced nasopharyngeal carcinoma : A matched-pair multicenter analysis of outcomes.

PURPOSE: The benefit of adjuvant chemotherapy (AC) in locoregionally advanced nasopharyngeal carcinoma (NPC) is controversial. This study compared concurrent chemoradiotherapy plus AC (CCRT/AC) with CCRT. METHODS: Pair-matched analysis based on eight clinicopathological features of 244 patients treated with platinum-based CCRT/AC or CCRT alone was performed. Survival outcomes were assessed using the Kaplan-Meier method and log-rank test. Toxicities and response rates were compared using Fisher's exact test. RESULTS: Four-year overall survival, progression-free survival, distant failure-free survival, and locoregional failure-free survival were 72 %, 61 %, 71 %, and 81 %, respectively, for the CCRT arm, compared to 74 % (hazard ratio, HR 0.89; 95 % confidence interval, CI 0.64-1.23; P = 0.474), 62 % (HR 0.91, 95 % CI 0.68-1.20, P = 0.489), 73 % (HR 0.84, 95 % CI 0.59-1.18, P = 0.316), and 84 % (HR 0.84, 95 % CI 0.52-1.24, P = 0.323), respectively, for the CCRT/AC arm. Cox multivariate regression analysis demonstrated AC was not an independent prognostic factor. Overall, there was a higher incidence of grade 3-4 toxicities in the CCRT/AC arm. The most common grade 3-4 adverse events in the CCRT/AC arm were vomiting (27 %), nausea (43 %), leukopenia/neutropenia (23 %), thrombocytopenia (8.8 %), and anemia (6.2 %). CONCLUSION: Addition of AC to CCRT increased toxicities but did not improve survival in locoregionally advanced NPC.

Raltitrexed plus oxaliplatin-based transarterial chemoembolization in patients with unresectable hepatocellular carcinoma.

Raltitrexed has shown efficacy and safety in many tumor types; however, the clinical data on the treatment of hepatocellular carcinoma is rare. In this report, we aim to assess the efficacy and safety of raltitrexed plus oxaliplatin (OXA)-based transarterial chemoembolization (TACE) in patients with unresectable hepatocellular carcinoma (uHCC). Patients with uHCC were recruited from multi-centers in China and assigned randomly to raltitrexed+OXA-based (n=76), fluorouracil+OXA-based (n=76), and doxorubicin+OXA-based (n=75) TACE treatment. The primary end point was overall survival (OS). Tumor response was assessed using response evaluation criteria in solid tumors (RECIST), modified response evaluation criteria in solid tumors (mRECIST), and European Association for the Study of the Liver criteria (EASL). Safety and toxicity were evaluated using the National Cancer Institute Common Toxicity Criteria. The raltitrexed group showed a better disease control rate evaluated using RECIST (raltitrexed vs. fluorouracil vs. doxorubicin: 96.1 vs. 84.2 vs. 86.7%, P=0.05) and a better overall response rate on the basis of mRECIST (67.1 vs. 47.4 vs. 50.7%, P=0.03) and EASL (67.1 vs. 47.4 vs. 49.3%, P=0.02). The median OS and median progression-free survival (PFS) were higher in the raltitrexed group (median OS: 13.4 vs. 9.6 vs. 8.5 months; median PFS: 6.7 vs 4.9 vs 4.6 months). The most common toxicities included elevated aspartate aminotransferase (78.9 vs. 86.8 vs. 81.3%) and abdominal nonspecific pain (68.4 vs. 81.6 vs. 78.7%). No significant differences were found in the overall number of patients who experienced any toxicity. Raltitrexed plus OXA-based TACE suggested a safe and efficacious regimen in uHCC patients. The results warrant further clinical investigation.

Changing hydration level in an internal cavity modulates the proton affinity of a key glutamate in cytochrome c oxidase.

Cytochrome c oxidase contributes to the transmembrane proton gradient by removing two protons from the high-pH side of the membrane each time the binuclear center active site is reduced. One proton goes to the binuclear center, whereas the other is pumped to the low-pH periplasmic space. Glutamate 286 (Glu286) has been proposed to serve as a transiently deprotonated proton donor. Using unrestrained atomistic molecular dynamics simulations, we show that the size of and water distribution in the hydrophobic cavity that holds Glu286 is controlled by the protonation state of the propionic acid of heme a3, a group on the proton outlet pathway. Protonation of the propionate disrupts hydrogen bonding to two side chains, allowing a loop to swing open. Continuum electrostatics and atomistic free-energy perturbation calculations show that the resultant changes in hydration and electrostatic interactions lower the Glu proton affinity by at least 5 kcal/mol. These changes in the internal hydration level occur in the absence of major conformational transitions and serve to stabilize needed transient intermediates in proton transport. The trigger is not the protonation of the Glu of interest, but rather the protonation of a residue ∼10 Šaway. Thus, unlike local water penetration to stabilize a new charge, this finding represents a specific role for water molecules in the protein interior, mediating proton transfers and facilitating ion transport.

Molecular mechanisms for generating transmembrane proton gradients.

Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.

[Establishment of rabbit with acute cerebral infarction by intervention and evaluation of computed tomographic perfusion imaging].

OBJECTIVE: To discuss the establishment of acute cerebral infarction model in rabbits and evaluate the value of computed tomographic perfusion (CTP) imaging. METHODS: A total of 12 healthy adult New Zealand white rabbits were used. The model was established through femoral artery puncture and injecting autoblood clot into internal carotid artery through an inserted micro-catheter to occlude the artery. Digital subtraction angiography (DSA) cerebral angiography and CTP imaging were performed at 2 and 6 hours post-embolization. RESULTS: Super-selective catheterization of internal carotid artery and an injection of auto-blood clots were successfully accomplished in all rabbits and the success rate was 100%. DSA showed that middle cerebral artery and anterior cerebral artery narrowed. At 2 hours post-embolism, CTP showed cerebral blood flow (CBF) and cerebral blood volume (CBV) decreased and mean transit time (MTT) and time to peak (TTP) increased in cerebral ischemia area. Compared with the contralateral mirror area, CBF and CBV decreased in infarct area and MTT and TTP elongated with significant statistical difference at 2 and 6 hours (P < 0.01). CONCLUSION: The model of acute cerebral ischemia may be effectively established in rabbits. This micro-invasive technique is easily manipulated with a high success rate. And CTP is an effective way of diagnosing acute cerebral infarction.

Surface Treatment with Tailored π-Conjugated Fluorene Derivatives Significantly Enhances the Performance of Perovskite Light-Emitting Diodes.

Surface defect passivation and carrier injection regulation have emerged as effective strategies for enhancing the performance of perovskite light-emitting diodes (Pero-LEDs). It usually requires two functional molecules to realize defect passivation and carrier injection regulation separately. In other words, developing one single molecule possessing these capabilities remains challenging. Herein, we utilized π-conjugated fluorene derivatives as surface treatment materials, 9,9-Spirobi[fluorene] (SBF), 9,9-Spirobifluoren-2-yl-diphenylphosphine oxide (SPPO1), and 2,7-bis(diphenylphosphoryl)-9,9'-spirobifluorene (SPPO13), to investigate the influence of their chemical structure on device optoelectronic performance, especially for defect passivation and carrier injection regulation. Consequently, the passivation capability of double-bonded SPPO13 surpassed single-bonded SPPO1 and nonbonded SBF, which all showed excellent electron transport properties, enhancing electron injection. The maximum external quantum efficiencies (EQE) for Pero-LEDs treated with SBF, SPPO1, and SPPO13 were 8.13, 17.48, and 22.10%, respectively, exceeding that of the derivative-free device (6.55%). Notably, SPPO13-treated devices exhibited exceptional reproducibility, yielding an average EQE of 20.00 ± 1.10% based on 30 devices. This result emphasizes the potential of tailored fluorene derivatives for enhancing the device performance of Pero-LEDs.

Diagnostic Accuracy of Transthoracic Echocardiography for Acute Type A Aortic Syndrome: A Systematic Review and Meta-Analysis.

BACKGROUND: Transthoracic echocardiography (TTE) is currently recognized as the potential first-line imaging test for patients with suspected acute type A aortic syndrome (AAAS). Direct TTE sign for detecting AAAS is positive if there is an intimal flap separating two aortic lumens or aortic wall thickening seen in the ascending aorta. Indirect TTE sign indicates high-risk features of AAAS, such as aortic root dilatation, pericardial effusion, and aortic regurgitation. Our aim is to summarize the existing clinical evidence regarding the diagnostic accuracy of TTE and to evaluate its potential role in the management of patients with suspected AAAS. METHODS: We included prospective or retrospective diagnostic cohort studies, written in any language, that specifically focused on using TTE to diagnose AAAS from databases such as PubMed, EMBASE, MEDLINE, and the Cochrane Library. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio [1], and hierarchical summary receiver-operating characteristic (HSROC) curve were calculated for TTE in diagnosing AAAS. We applied Quality Assessment of Diagnostic Accuracy (QUADAS-2) tool and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) quality assessment criteria. RESULTS: Ten studies (2886 patients) were included in the meta-analysis. The pooled sensitivity and specificity of direct TTE signs were 58% (95% CI, 38-76%) and 94% (95% CI, 89-97%). For any TTE signs, the pooled sensitivity and specificity were 91% (95% CI, 85-94%) and 74% (95% CI, 61-84%). The diagnostic accuracy of direct TTE signs was significantly higher than that of any TTE signs, as measured by the area under the HSROC curve [0.95 (95% CI, 0.92-0.96) vs. 0.87 (95% CI, 0.84-0.90)] in four studies. CONCLUSIONS: Our study suggests that TTE could serve as the initial imaging test for patients with suspected AAAS. Given its high specificity, the presence of direct TTE signs may indicate AAAS, whereas the absence of any TTE signs, combined with low clinical suspicion, could suggest a lower likelihood of AAAS.

Correlations of PCSK9 and LDLR Gene Polymorphisms and Serum PCSK9 Levels With Atherosclerosis and Lipid Metabolism in Patients on Maintenance Hemodialysis.

This study is aimed at investigating the correlations of PCSK9 and LDLR gene polymorphisms as well as serum proprotein convertase subtilisin/kexin type 9 (PCSK9) levels with atherosclerosis and lipid metabolism in patients on maintenance hemodialysis (HD). A single nucleotide polymorphism at the E670G locus of the PCSK9 gene and the rs688 locus of the LDLR gene was analyzed by polymerase chain reaction-restriction fragment length polymorphism. All study subjects' blood lipid (triglyceride [TG], total cholesterol [TC], high-density lipoprotein cholesterol [HDL-C], and low-density lipoprotein cholesterol [LDL-C]) concentrations and lipoprotein(a) and PCSK9 levels were measured. The differences in blood lipid levels between different genotypes of the E670G locus of the PCSK9 gene and the rs688 locus of the LDLR gene in patients on maintenance HD with atherosclerosis were compared. Patients on maintenance HD with atherosclerosis at the E670G locus of the PCSK9 gene AG + GG genotype had higher levels of TG, TC, LDL-C, and lipoprotein(a) than the AA genotype, and lower levels of HDL-C than the AA genotype. Patients on maintenance HD with atherosclerosis at the rs688 locus of the LDLR gene CT + TT genotype had higher levels of TG, TC, LDL-C, and lipoprotein(a) than the CC genotype, and lower levels of HDL-C than the CC genotype. Serum PCSK9 contents in patients on maintenance HD with atherosclerosis were positively correlated with lipid indices (TG, TC, LDL-C, and lipoprotein(a)) and carotid ultrasound indices (intima-media thickness and resistance index), and negatively correlated with HDL-C, maximum systolic blood flow velocity, and minimum diastolic blood flow velocity (all P < .05).