Loading of AuNCs with AIE effect onto cerium-based MOFs to boost fluorescence for sensitive detection of Hg2. Talanta 2024;273:125843. [PMID: 38492285 DOI: 10.1016/j.talanta.2024.125843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Ligand-protected gold nanoclusters (AuNCs) have become promising nanomaterials in fluorescence (FL) methods for mercury ions (Hg2+) monitoring, but low FL efficiency hinders their widespread application. Herein, AuNCs/cerium-based metal-organic frameworks (AuNCs/Ce-MOFs) were prepared by loading 6-aza-2-thiothymine-protected AuNCs (ATT-AuNCs) with aggregation-induced emission (AIE) effect on the surface of Ce-MOFs by electrostatic attraction. This strategy improved the FL intensity of AuNCs through two aspects: (i) the AIE effect of ATT-AuNCs and (ii) the confinement effect of Ce-MOFs, which improved the restriction of intramolecular motion (RIM) of ATT-AuNCs. In addition, Ce-MOFs could adsorb and aggregate Hg2+ during detection, which might increase the local concentration. Therefore, based on the high FL signal of AuNCs/Ce-MOFs and enriched Hg2+, sensitive detection of Hg2+ could be achieved. More importantly, the strong specific recognition between AuNCs and Hg2+ could guarantee selectivity. The developed FL sensor exhibited superior detection performances with a wide linear range of 0.2-500 ng mL-1 and a low detection limit of 0.067 ng mL-1. Furthermore, the FL sensor used for sensitive and selective detection of Hg2+ in real samples, and the results agreed well with the standard method. In summary, this work proposed an effective and generalized strategy for improving the FL efficiency of AuNCs, which would greatly facilitate their application in pollutant monitoring.

Isolation of Sensing Units and Adsorption Groups Based on MOF-on-MOF Hierarchical Structure for Both Highly Sensitive Detection and Removal of Hg2

Bifunctional materials have attracted ongoing interest in the field of detection and removal of contaminants because of their integration of two functions, but they exhibit commonly exceptional performance in only one of these two aspects. The interaction between the two functional units of the bifunctional materials may compromise their sensing and adsorption abilities. Guided by the concept of domain building blocks (DBBs), a hierarchical metal-organic framework (MOF)-on-MOF hybrid was designed by growing gold nanoclusters (AuNCs)-embedded zeolitic imidazolate framework 8 (AuNCs/ZIF-8) on the surface of Zr-MOF (UiO-66-NH2) for the simultaneous detection and removal of Hg2+. In the hybrid, the amino groups (-NH2) and AuNCs─which were the adsorption groups and sensing units, respectively, were isolated from each other. Specifically, the adsorption groups (-NH2) were assembled in the inner UiO-66-NH2 layer, while the sensing units (AuNCs) were confined in the outer ZIF-8 layer. This hierarchical structure not only spatially hindered the electron transfer between these two units but also triggered the aggregation-induced emission of AuNCs because of the confinement of ZIF-8 on the AuNCs, thus changing the fluorescence of AuNCs from quenching to enhancement. The newly prepared UiO-66-NH2@AuNCs/ZIF-8 hybrid, as expected, showed an ultralow detection limit (0.42 ppb) and a high adsorption capacity (129.9 mg·g-1) for Hg2+. Overall, this work provides a feasible approach to improve the integrated performance of MOF-based composites based on DBBs.

Simple and sensitive fluorescence sensing of methyl parathion based on the inner filter effect of p-nitrophenol on nitrogen-doped titanium carbide quantum dots

It is of great significance to develop an effective method for methyl parathion (MP) detection. Herein, a novel nitrogen-doped titanium carbide quantum dots (N-Ti3 C2 QDs) was prepared and used to construct a simple and sensitive fluorescence sensing platform of MP by making use of inner filter effect (IFE). The prepared N-Ti3 C2 QDs can exhibit strong blue fluorescence at 434 nm. Meanwhile, MP could hydrolyze to produce p-nitrophenol (p-NP) under alkaline conditions, which showed a characteristic ultraviolet-visible (UV-visible) absorption peak at 405 nm, resulting in the fluorescence of N-Ti3 C2 QDs is effectively quenched by p-NP. In addition, the investigation of time-resolved fluorescence decays indicated that the corresponding quenching mechanism of p-NP on N-Ti3 C2 QDs is due to the IFE. After optimizing the conditions, the as-developed fluorescence sensing platform displayed wide detection range (0.1-30 μg mL-1 ) and low detection limit (0.036 μg mL-1 ) for MP, and it was also successfully applied for MP analysis in real water samples, thus it is expected that this simple, sensitive and enzyme-free sensing platform shows great applications.

Molecular screening of Entamoeba spp. (E. histolytica, E. dispar, E. coli, and E. hartmanni) and Giardia intestinalis using PCR and sequencing

A wide range of intestinal protozoan parasites inhabit the human gut. To establish a more comprehensive molecular screening, we designed PCR-sequencing screening methods for Entamoeba spp., including commensal species, and Giardia intestinalis, and performed such methods using 174 stool samples collected from Kenyan children. The prevalences of the target species were as follows: E. histolytica (2/174, 1.1%), E. dispar (20/174, 11.5%), E. coli (107/174, 61.5%), E. hartmanni (77/174, 44.3%), and G. intestinalis (54/174, 31.0%). PCR amplicons specific to G. intestinalis was differentiated to assemblages A (8/174, 4.6%) and B (46/174, 26.4%). PCR specificity for Entamoeba spp. was quite high, except for some cross-reactions between E. hartmanni detection primers and G. intestinalis, although the false-positive amplicons were discernible by the band size. The 18S rRNA PCR primers that was designed by Monis et al. in 1999 for G. intestinalis, have specificity issue, therefore amplicon sequencing was essential not only to determine assemblage classifications but also to confirm the positive results by eliminating potential non-specific reactions. The detection sensitivity of both the Entamoeba universal PCR and the G. intestinalis PCR was more than 100 copies of the target loci, which is sufficient for detecting a single trophozoite or cyst of both species.

Advances in the application of metal-organic framework nanozymes in colorimetric sensing of heavy metal ions

Nanozymes, which can be defined as nanomaterials with excellent catalytic function, are well known to the scientific community due to their distinct merits, such as low cost and high stability, which render them preferable to natural enzymes. As porous organic-inorganic coordination materials, metal-organic frameworks (MOFs) possess a large number of active sites and thus can effectively mimic the properties of natural enzymes. Recently, MOF-based nanozymes have also exhibited good application potential for the analysis of heavy metal ions. In comparison to the traditional detection methods for heavy metal ions, nanozyme-based colorimetric sensing permits intuitive visual analysis by using relatively simple instruments, facilitating rapid and simple on-site screening. In this minireview, the preparation of MOF-based nanozymes and the different nanozyme activity types are briefly described, such as peroxidase-like and oxidase-like, and the relevant catalytic mechanisms are elaborated. Based on this, different response mechanisms of MOF-based colorimetric methods to heavy metal ions, such as turn-off, turn-on, and turn-off-on, are discussed. In addition, the colorimetric sensing applications of MOF-based nanozymes for the detection of heavy metal ions are summarized. Finally, the current research status of MOF-based nanozymes and the future development direction are discussed.

[Bioinformatics analysis and prokaryotic expression of Strongyloides stercoralis serine protease inhibitor 1]

OBJECTIVE

To predict the structure and antigenic epitope of the Strongyloides stercoralis serine protease inhibitor 1 (Ss-SRPN-1) protein using bioinformatics tools, and to construct prokaryotic expression plasmids for expression of recombinant Ss-SRPN-1 protein, so as to provide the basis for unraveling the function of the Ss-SRPN-1 protein.

METHODS

The amino acid sequence of the Ss-SRPN-1 protein was downloaded from the NCBI database, and the physicochemical properties, structure and antigenic epitopes of the Ss-SRPN-1 protein were predicted using bioinformatics tools, including ExPASy, SWISS-MODEL and Protean. Primers were designed according to the nucleotide sequences of Ss-SRPN-1, and the Ss-SRPN-1 gene was amplified, cloned and sequenced with genomic DNA extracted from the infective third-stage larvae of S. stercoralis as a template. The Ss-SRPN-1 protein sequence was cloned into the pET28a (+) expression vector and transformed into Escherichia coli BL21 (DE) cells for induction of the recombinant Ss-SRPN-1 protein expression. The recombinant Ss-SRPN-1 protein was then purified and identified using Western blotting and mass spectrometry.

RESULTS

Bioinformatics analysis showed that the Ss-SRPN-1 protein, which was composed of 372 amino acids and had a molecular formula of C₁₉₄₈H₃₀₄₆N₄₈₈O₅₇₅S₁₆, was a stable hydrophilic protein, and the subcellular localization of the protein was predicted to be extracellular. The Ss-SRPN-1 protein was predicted to contain 11 dominant B-cell antigenic epitopes and 20 T-cell antigenic epitopes. The Ss-SRPN-1 gene with a length of 1 119 bp was successfully amplified, and the recombinant plasmid pET28a (+)/Ss-SRPN-1 was constructed and transformed into E. coli BL21(DE) cells. The expressed recombinant Ss-SRPN-1 protein had a molecular weight of approximately 43 kDa, and was characterized as a Ss-SRPN-1 protein.

CONCLUSIONS

The recombinant Ss-SRPN-1 protein has been expressed successfully, and this recombinant protein may be a potential vaccine candidate against strongyloidiasis.

Gold nanocluster-confined covalent organic frameworks as bifunctional probes for electrochemiluminescence and colorimetric dual-response sensing of Pb2

The development of bifunctional signal probes based on a single component is highly desirable for sensitive and simple dual-mode detection of Pb²⁺. Here, novel gold nanocluster-confined covalent organic frameworks (AuNCs@COFs) were fabricated as a bisignal generator to enable electrochemiluminescence (ECL) and colorimetric dual-response sensing. AuNCs with both intrinsic ECL and peroxidase-like activity were confined into the ultrasmall pores of the COFs via an in situ growth method. On the one hand, the space-confinement effect of the COFs closed the ligand motion-induced nonradiative transition channels of the AuNCs. As a result, the AuNCs@COFs exhibited a 3.3-fold enhancement in anodic ECL efficiency compared to the solid-state aggregated AuNCs using triethylamine as the coreactant. On the other hand, due to the outstanding spatial dispersibility of the AuNCs in the structurally ordered COFs, a high density of active catalytic sites and accelerated electron transfer were obtained, leading to the promotion of the enzyme-like catalytic capacity of the composite. To validate its practical applicability, a Pb²⁺-triggered dual-response sensing system was proposed based on the aptamer-regulated ECL and peroxidase-like activity of the AuNCs@COFs. Sensitive determinations down to 7.9 pM for the ECL mode and 0.56 nM for the colorimetric mode were obtained. This work provides an approach for designing single element-based bifunctional signal probes for dual-mode detection of Pb²⁺.

[Expression of CD47 and its ligands in pregnant mice infected with Toxoplasma gondii during pregnancy]

OBJECTIVE

To investigate the dynamic expression of cluster of differentiation 47 (CD47) and its ligands signaling regulatory protein α (SIRPα) and thrombospondin-1 (TSP-1) in mice infected with Toxoplasma gondii in the second and third trimesters.

METHODS

C57BL/6J mice (6 to 8 weeks old) were used for modeling T. gondii infection in the first trimester, and the pregnant mice were randomly divided into the normal control and infection groups, of 10 mice in each group. Pregnant mice in the infection group were intraperitoneally injected with 150 T. gondii tachyzoites on gestational day (Gd) 6.5, while pregnant mice in the normal control group were intraperitoneally injected with the same volume of physiological saline at the same time. The uterine and placental specimens were collected from all pregnant mice on Gd12.5 and Gd18.5, and the pregnant outcomes were recorded. The pathological damages of mouse uterine and placental specimens were observed using hematoxylin-eosin (HE) staining on Gd12.5 and Gd18.5. The relative expression of CD47, SIRPα, TSP-1, surface antigen 1 (SAG1), interferon-γ (IFN-γ), interleukin-2 (IL-2), IL-4 and IL-13 mRNA was quantified in mouse uterine and placental specimens using real-time fluorescence quantitative PCR (qPCR) assay, and the CD47, SIRPα, TSP-1 expression was determined in mouse uterine and placental specimens using immunohistochemical staining.

RESULTS

As compared with those in the normal control group, the pregnant mice in the infection group showed back arching, bristling, trembling and listlessness during pregnancy, and several mice presented virginal bleeding and abortion. Pathological examinations showed inflammatory cell infiltration, congestion and necrosis in uterine and placental specimens of pregnant mice in the infection group, a higher abortion rate of pregnant mice was seen in the infection group than in the normal control group on Gd12.5 (χ² = 20.405, P < 0.001) and Gd18.5 (χ² = 28.644, P < 0.001). qPCR assay showed significant differences in the expression of CD47, SIRPα, TSP-1, SAG1, INF-γ, IL-2, IL-4 and IL-13 genes in mouse placental specimens between the normal control and infection groups on Gd12.5 and Gd18.5 [F' (F) = 37.511, 29.337, 97.343, 53.755, 67.188, 21.145, 8.658 and 13.930, all P values < 0.001]. Higher CD47, SIRPα and TSP-1 gene expression was quantified in mouse placental specimens in the infection group than in the normal control group on Gd12.5 (all P values < 0.01), and lower CD47, SIRPα and TSP-1 gene expression was quantified in the infection group than in the normal control group on Gd18.5 (all P values < 0.001), while higher SAG1 gene expression was detected in placental specimens of pregnant mice in the infection group than in the normal control group on Gd12.5 and Gd18.5 (both P values < 0.01). In addition, higher INF-γ and IL-2 expression and lower IL-4 and IL-13 expression was detected in mouse placental specimens in the infection group than in the normal control group on Gd12.5 and Gd18.5 (all P values < 0.001), and there were significant differences in the CD47, SIRPα, TSP-1, SAG1, INF-γ, IL-2, IL-4 and IL-13 gene expression in uterine specimens of pregnant mice between the normal control and infection groups on Gd12.5 and Gd18.5 [H(F' and F) = 14.951, 25.977, 18.711, 48.595, 39.318, 14.248 and 15.468, all P values < 0.01], and higher CD47 and TSP-1 expression was detected in mouse uterine specimens in the infection group than in the control group on Gd12.5 and Gd18.5 (all P values < 0.01); however, no significant difference was found in the SIRPα expression (P > 0.05). Higher SAG1 expression was detected in uterine specimens of pregnant mice in the infection group than in the normal control group on Gd12.5 and Gd18.5 (both P values < 0.01), and higher INF-γ and IL-2 gene expression and lower IL-4 and IL-13 gene expression was found in the placental specimens of pregnant mice in the infection group than in the normal control group on Gd12.5 and Gd18.5 (all P values < 0.001). Spearman correlation analysis showed that the CD47 gene expression correlated positively with IFN-γ (r_s = 0.735, P < 0.05) and IL-2 (r_s = 0.655, P < 0.05) and negatively with IL-4 (r_s = -0.689, P < 0.05) and IL-13 expression (r_s = -0.795, P < 0.05) in the placental specimens of pregnant mice in the infection group on Gd12.5, and the CD47 gene expression correlated negatively with IFN-γ (r_s = -0.745, P < 0.05) and IL-2 expression (r_s = -0.816, P < 0.05) and positively with IL-4 (r_s = 0.704, P < 0.05) and IL-13 (r_s = 0.802, P < 0.05) in the placental specimens of pregnant mice in the infection group on Gd18.5. Immunohistochemical staining showed mild CD47, SIRPα and TSP-1 expression in uterine and placental specimens of pregnant mice in the normal control group on Gd12.5 and Gd18.5, strong CD47, SIRPα and TSP-1 expression in the placental specimens of pregnant mice in the infection group on Gd12.5 and strong CD47 and TSP-1 expression in the uterine specimens of pregnant mice in the infection group on Gd12.5.

CONCLUSIONS

T. gondii infection in the first trimester may cause abnormal expression of CD47 and its ligands SIRPα and TSP-1 in the maternal-fetal interface of pregnant mice in the second and third trimesters, which may be associated with the immune escape of T. gondii at the maternal-fetal interface.

Highly Fluorescent Magnetic ATT-AuNCs@ZIF-8 for All-in-One Detection and Removal of Hg2+: An Ultrasensitive Probe to Evaluate Its Removal Efficiency

The development of multifunctional materials for the synchronous detection and removal of mercury ions (Hg²⁺) is in high demand. Although a few multifunctional materials as a fluorescent indicator and adsorbent have achieved this aim, the feedback of their removal efficiency still depends on other methods. Herein, magnetic Fe₃O₄ nanoparticles (MNPs) and 6-aza-2-thiothymine-protected gold nanoclusters (ATT-AuNCs) were rationally assembled into a zeolitic imidazolate framework 8 (ZIF-8) structure via a one-pot method. The coordination assembly of ATT-AuNCs and ZIF-8 not only strengthened the aurophilic interactions of adjacent ATT-AuNCs but also induced the restriction of intramolecular motion of ATT with a six-membered heterocyclic structure. As a consequence, the fluorescence (FL) quantum yield of MNPs/ATT-AuNCs@ZIF-8 was 12.5-fold higher than that of pristine ATT-AuNCs. Benefiting from the enhanced FL emission, MNPs/ATT-AuNCs@ZIF-8 showed improved sensitivity for Hg²⁺ detection and therefore could evaluate the removal efficiency via FL detection, without relying on another detection method. Additionally, the nanocomposite also displayed a satisfactory removal capability for Hg²⁺, including a short capture time (20 min), a high removal efficiency (>96.9%), and excellent reusability (10 cycles). This work provides an approach for customizing functional nanocomposites to concurrently detect and remove Hg²⁺ with superior performance, especially for high detection sensitivity.

Dual-quenching effects of methylene blue on the luminophore and co-reactant: Application for electrochemiluminescent-electrochemical ratiometric zearalenone detection

Methylene blue (MB) is a common multifunctional indicator, which can be applied as a quencher for electrochemiluminescence (ECL) analysis as well as a classical redox probe. Although it is relatively prevalent for MB to study the mechanism with Ru-based luminophores in ECL systems, there are few studies on the effects between MB and co-reactants. In this work, we proposed the first investigation of MB on the luminophore and co-reactant of the self-enhanced ECL composites (nitrogen-doped graphene quantum dots on Ru(bpy)₃²⁺-doped silica nanoparticles, NGQDs-Ru@SiO₂), respectively. The relatively narrow ECL spectrum of luminophore (Ru@SiO₂) and the suitable ultraviolet-visible absorption spectrum of MB led to the ECL resonance energy transfer between them, meanwhile the appropriate energy levels among them facilitated the electron transfer, resulting in a decreased ECL signal (quench mode I). Additionally, the co-reactant (NGQDs) was prone to π-π conjugation with MB due to its abundant π-electrons, which reduced the concentration of NGQDs' intermediates and triggered a weakened ECL signal (quench mode II). Therefore, the dual-quenching effects are ingeniously integrated and designed in one ECL-electrochemical (ECL-EC) ratiometric aptasensor for zearalenone detection, for demonstrating its efficacy in enhancing the sensitivity, which is 4.8-fold higher than Ru@SiO₂ alone. This innovative ratiometric aptasensor achieved a relatively wide linear range from 1.0 × 10^-15 to 5.0 × 10^-8 g mL^-1, and obtained a low detection limit of 8.5 × 10^-16 g mL^-1. Our proposed dual-quenching interactions between MB and NGQDs-Ru@SiO₂ will open a new prospective for ECL-EC ratiometric aptasensor, which further broaden the application in sensitive and precise analysis of mycotoxins.

An ultra-high-sensitivity electrochemiluminescence aptasensor for Pb2+ detection based on the synergistic signal-amplification strategy of quencher abscission and G-quadruplex generation

Signal amplification provides an effective way to improve detection performance. Herein, an ultrasensitive electrochemiluminescence (ECL) aptasensor for Pb²⁺ detection was developed based on a dual signal-amplification strategy of the abscission of a quencher and the generation of a G-quadruplex by one-step and simultaneous way. Nitrogen-doped carbon quantum dots linked with complementary DNA (cDNA-NCQDs) at the sensing interface was applied as the quencher of a tris(4,4'-dicarboxylic acid-2,2'-bipyridyl)ruthenium(II) (Ru(dcbpy)₃²⁺)/tripropylamine system to minimize the ECL signal due to the intermolecular hydrogen bond-induced energy-transfer process. Upon the addition of Pb²⁺, its specific binding with the aptamer triggered the abscission of cDNA-NCQDs, accompanied by the formation of G-quadruplex on the surface of the electrode, both of which amplified the intensity of the light emission. The ECL amplification efficiency induced by the above two mechanisms (78.6%) was valuably greater than that of their sum value (69.3%). This synergistic effect resulted in high detection sensitivity of the ECL aptasensor, which allowed to thereby obtain Pb²⁺ measurements in the range of 1 fM - 10 nM with an ultra-low detection limit of 0.19 fM. The Pb²⁺-mediated synergistic signal-amplification ECL strategy can provide a new approach for integrating various amplification strategies.

Induced self-enhanced electrochemiluminescence aptamer sensor for 17β-estradiol detection based on nitrogen-doped carbon quantum dots as Ru(dcbpy)32+ coreactant: What role of intermolecular hydrogen bonds play in the system?

Herein, an induced self-enhanced electrochemiluminescence (ECL) sensor with superior ECL performances was simply fabricated by just dropping the ECL reagent (tris(4,4'-dicarboxylicacid-2,2'-bipyridyl) ruthenium (II) dichloride, Ru(dcbpy)₃Cl₂) and coreactant (nitrogen-doped carbon quantum dots, NCQDs) pair onto the surface of glassy carbon electrode. In this strategy, based on the carboxyl (-COOH) groups in Ru(dcbpy)₃²⁺ and oxygen, nitrogen-containing groups on NCQDs surface, an intermolecular hydrogen bonds-induced self-enhanced ECL composite was generated in the solid contact layer for the first time. Since Ru(dcbpy)₃²⁺ and NCQDs were co-existing in the same composite, the electron-transfer distance between them was shortened and the energy loss was decreased, thereby higher ECL efficiency was acquired. This working process greatly avoided the introduction of signal amplifier and simplified the experimental operation. On this basis, 17β-estradiol (E2) was selected as a target model to fabricate a self-enhanced ECL aptamer sensor for the investigation of its analytical performances. Resultantly, excellent detection properties of E2, including wider linear range of 1.0 × 10^-14 - 1.0 × 10^-6 mol L^-1 and lower detection limit of 1.0 × 10^-15 mol L^-1 with superior selectivity, were successfully achieved. Finally, E2 spiked into milk powder was quantified to assess the practicability of this sensor. Prospectively, this strategy could be extensively applied for other analytes determination by adjusting the corresponding target aptamers.

Inner filter effect-modulated ratiometric fluorescence aptasensor based on competition strategy for zearalenone detection in cereal crops: Using mitoxantrone as quencher of CdTe QDs@SiO2

Herein, an innovative ratiometric fluorescence (FL) aptasensor was successfully fabricated for the accurate analysis of zearalenone (ZEN) in corn and barley flour. The ZEN aptamer-modified nitrogen doped graphene quantum dots (NGQDs-apt) and silica sphere-encapsulated cadmium telluride quantum dots (CdTe QDs@SiO₂) were directly mixed and applied as ratiometric probes. In the absence of ZEN, mitoxantrone (MTX), which was innovatively introduced as quencher, was captured by NGQDs-apt and its inner filter effect (IFE) on CdTe QDs@SiO₂ was inhibited. When ZEN existed, MTX separated from NGQDs-apt and re-dispersed around CdTe QDs@SiO₂ owing to the competitive binding of ZEN with its aptamer. As the IFE of free MTX on CdTe QDs@SiO₂ recovering, the FL intensity of CdTe QDs@SiO₂ was quenched, while the FL intensity of NGQDs-apt was nearly invariant. On this basis, a ratiometric FL aptasensor for ZEN was fabricated, which exhibited outstanding detection performances with a desirable detection limit of 0.32 pg mL^-1.

Cerebral Venous Thrombosis: MR Black-Blood Thrombus Imaging with Enhanced Blood Signal Suppression

BACKGROUND AND PURPOSE

The residual blood flow artifact is a critical confounder for MR black-blood thrombus imaging of cerebral venous sinus thrombosis. This study aimed to conduct a validation of a new MR black-blood thrombus imaging technique with enhanced blood signal suppression.

MATERIALS AND METHODS

Twenty-six participants (13 volunteers and 13 patients) underwent conventional imaging methods followed by 2 randomized black-blood thrombus imaging scans, with a preoptimized delay alternating with nutation for tailored excitation (DANTE) preparation switched on and off, respectively. The signal intensity of residual blood, thrombus, brain parenchyma, normal lumen, and noise on black-blood thrombus images were measured. The thrombus volume, SNR of residual blood, and contrast-to-noise ratio for residual blood versus normal lumen, thrombus versus residual blood, and brain parenchyma versus normal lumen were compared between the 2 black-blood thrombus imaging techniques. Segmental diagnosis of venous sinus thrombosis was evaluated for each black-blood thrombus imaging technique using a combination of conventional imaging techniques as a reference.

RESULTS

In the volunteer group, the SNR of residual blood (11.3 ± 2.9 versus 54.0 ± 23.4, P < .001) and residual blood-to-normal lumen contrast-to-noise ratio (7.5 ± 3.4 versus 49.2 ± 23.3, P < .001) were significantly reduced using the DANTE preparation. In the patient group, the SNR of residual blood (16.4 ± 8.0 versus 75.0 ± 35.1, P = .002) and residual blood-to-normal lumen contrast-to-noise ratio (12.4 ± 7.8 versus 68.8 ± 35.4, P = .002) were also significantly lower on DANTE-prepared black-blood thrombus imaging. The new black-blood thrombus imaging technique provided higher thrombus-to-residual blood contrast-to-noise ratio, significantly lower thrombus volume, and substantially improved diagnostic specificity and agreement with conventional imaging methods.

CONCLUSIONS

DANTE-prepared black-blood thrombus imaging is a reliable MR imaging technique for diagnosing cerebral venous sinus thrombosis.

[The protective effect of pigment epithelial-derived factor modified human umbilical cord mesenchymal stem cells on rats with diabetic retinopathy]

Objective: To investigate the effect of pigment epithelial-derived factor (PEDF) gene-modified human umbilical cord mesenchymal stem cells (MSC) on rats with diabetic retinopathy (DR). Methods: Experimental study. Human umbilical cord MSC were transfected by lentivirus packaging PEDF-MSC-green fluorescent protein (GFP) and GFP-MSC plasmid vectors, and the expression of PEDF and vascular endothelial growth factor (VEGF) was measured in the cell culture medium. Fifty adult male Sprague-Dawley rats were randomly divided into five groups: normal control group (group A), DR control group (group B), phosphate-buffered saline (PBS) treated group (group C), GFP-MSC treated group (group D) and PEDF-MSC-GFP treated group (group E), with 10 rats in each group. Streptozotocin was intraperitoneally injected to make early DR models. After four-month intervention, groups D and E were given intravitreal injection of GFP-MSC and PEDF-MSC-GFP; group C was given intravitreal injection of phosphate-buffered saline; groups A and B did not receive special treatment. The changes of retina in different groups were detected by hematoxylin and eosin staining, and the thickness of inner plexiform layer, inner nuclear layer and outer nuclear layer was measured by computer-based image analytical system. Immunohistochemistry was applied to observe PEDF and VEGF. Real-time quantitative polymerase chain reaction was used to detect the expression of PEDF and VEGF mRNA. Results: The expression of CD105, CD73 and CD90 was positive, while the expression of CD34, CD45, CD11b, CD19 and HLA-DR was negative. ELISA results showed that after transfection PEDF protein expression in the supernatant of PEDF-MSC (84.09±7.07) μg/L was higher than the control group (9.03±0.14) μg/L (P<0.05). At 2 weeks after intravitreal injection, green fluorescence was observed in the rat vitreous of groups D and E under a fluorescence microscope; no obvious green fluorescence was found in the retina. After 2 months of intravitreal injection, the thickness of inner plexiform layer in group E was significantly decreased; the thickness of inner nuclear layer and outer nuclear layer was higher (P<0.05). Immunohistochemical staining showed that 2 months after intravitreal treatment, the average optical density values of PEDF were improved, but the average optical density values of VEGF were decreased in group E (P<0.05). Real-time polymerase chain reaction showed that 2 months after treatment, the expression level of PEDF mRNA in group E was improved, but the expression level of VEGF mRNA was decreased (P<0.05). Conclusions: Intravitreal injection of PEDF-MSC could up-regulate the expression of PEDF and down-regulate the expression of VEGF in diabetic rats and may represent a novel candidate resource for cell therapy of DR nerve damage. (Chin J Ophthalmol, 2017, 53, 540-547).

Clinical, neuroimaging and prognostic study of 127 cases with infarction of the corpus callosum

Background and purpose

The aim of this study was to retrospectively investigate clinical and neuroimaging characteristics in the largest sample size of patients with corpus callosum infarction to date and then to follow up these patients for 1 year to clarify the prognosis of this rare stroke entity.

Methods

A total of 127 patients with acute callosal infarction out of 5584 acute ischaemic stroke patients were included in this study. The recruited patients were divided into a pure callosal infarction group and a complex callosal infarction group (coupled with other infarct locations simultaneously), and clinical and neuroimaging features were analyzed. Some of the patients were followed up for 1 year to evaluate recurrence rate and mortality.

Results

The incidence of acute callosal infarction was 2.3%. Most patients presented with advanced neurological dysfunction with or without mild to moderate motor or sensory disorders on admission. The negative rate of computed tomography scan was still 76.4% even at >24 h after onset. Large‐artery atherosclerosis was the most common etiological type. Compared with complex callosal infarction, the pure callosal infarction group had more mental disorders (P = 0.030). Compared with common basal ganglia infarction, the pure callosal infarction group had better short‐term recovery (P = 0.016) but higher 1‐year mortality (P = 0.037). Age and mental disorders were independent risk factors for death in callosal infarction.

Conclusions

Callosal infarction is a white matter stroke that occurs with low incidence. Elderly patients with vascular risk factors showed sudden mental or cognitive disorders and callosal infarction could not be excluded. More attention should be paid to the early diagnosis and secondary prevention of callosal infarction because of its poor long‐term outcome.

[Reliability and validity of the Chinese version on Comprehensive Scores for Financial Toxicity based on the patient-reported outcome measures]

Objective: To evaluate the reliability and validity of the Chinese version on comprehensive scores for financial toxicity (COST), based on the patient-reported outcome measures. Methods: A total of 118 cancer patients were face-to-face interviewed by well-trained investigators. Cronbach's α and Pearson correlation coefficient were used to evaluate reliability. Content validity index (CVI) and exploratory factor analysis (EFA) were used to evaluate the content validity and construct validity, respectively. Results: The Cronbach's α coefficient appeared as 0.889 for the whole questionnaire, with the results of test-retest were between 0.77 and 0.98. Scale-content validity index (S-CVI) appeared as 0.82, with item-content validity index (I-CVI) between 0.83 and 1.00. Two components were extracted from the Exploratory factor analysis, with cumulative rate as 68.04% and loading>0.60 on every item. Conclusion: The Chinese version of COST scale showed high reliability and good validity, thus can be applied to assess the financial situation in cancer patients.

CCAAT enhancer binding protein β promotes tumor growth and inhibits apoptosis in prostate cancer by methylating estrogen receptor β

The CCAAT enhancer binding protein β (C/EBPβ) is overexpressed at late stages in carcinogenesis of prostate cancer (PCa), suggesting that it could potentially contribute to progression of PCa. Estrogen receptor beta (ERβ) is a tumor suppressor gene in PCa. However, whether C/EBPβ could regulate ERβ by promoter methylation is still poorly understood.In this study, expression levels of C/EBPβ and ERβ in two PC lines (LNCap and PC-3), prostatic epithelial cell line (RWPE-1), forty-eight paired non-cancerous and cancerous peripheral blood samples were examined via qRT-PCR, western blotting and methylation-specific PCR. In addition, PCa cell line was infected with pCDH-C/EBPβ and pLKO.1-C/EBPβ and expression levels of C/EBPβ, ERβ and DNA methyltransferases were detected. Finally, the role of C/EBPβ in proliferation and apoptosis of PCa cell lines was examined by MTT and flow cytometer assay. Our results show a higher frequency of promoter methylation of ERβ levels in blood samples from PCa patients (16 of 48 cases) compared with that from healthy controls (3 of 48). Besides, elevated expression levels of C/EBPβ were found in PCa patients and two PCa lines (LNCap and PC-3) compared to non-cancerous cases or prostatic epithelial cell line (RWPE-1), while opposite expression levels of ERβ were found. Overexpression of C/EBPβ could regulate ERβ expression, DNA methyltransferases expression, cell proliferation and apoptosis. Our results support the conclusion that C/EBPβ down-regulated ERβ expression through increasing its promoter methylation, and then regulated proliferation and apoptosis in PCa.

[The protective effect of human umbilical cord mesenchymal stem cells-induced neural stem cells in the vitreous on the blood-retinal barrier in diabetic rats]

Objective: To investigate the effect of intravitreal injection of neural stem cells (NSC) induced from human umbilical cord mesenchymal stem cells, and to provide a theoretical basis for the clinical treatment of blood-retinal barrier damage due to diabetic retinopathy (DR). Methods: Experimental study. Sixty male Sprague-Dawley rats were randomly divided into control group, DR group and NSC group. Diabetic rats were induced by injection of streptozotocin, and the control rats were injected with an equal volume of solvent. Three months after the establishment of diabetic models, the NSC group was injected with 2 μl of NSC in the right vitreous, and the DR group was injected with 2 μl of phosphate-buffered saline. One month later, all the rats were sacrificed. The retinal vessels and leakage were examined with flat-mounted retinas. Vascular permeability was quantified by analyzing albumin leakage using the Evans blue (EB) method. Retina was examined by hematoxylin and eosin staining. Results: Retinal blood vessels of the control rats were normal, with no EB leakage outside the vessels. The background fluorescence was enhanced and focal leakage and focal dilated vessels were detected in the DR group. In the NSC group, background fluorescence was enhanced slightly and EB leakage area decreased significantly compared with the DR group. The average EB in control group, DR group and NSC group were (9.91±1.53), (24.67±2.26) and (12.85±2.58)μg/g, The EB leakage in the NSC group decreased significantly compared with the DR group (q=9.748, P<0.05). Pathological hematoxylin and eosin staining showed that the retinal layer structure was normal and clear in the control group, the retina was thin, the cell arrangement was in disorder and the nucleus was swelling in the DR group, the status of the NSC group was between the other two groups. Conclusions: Transferring human umbilical cord mesenchymal stem cells-induced NSC in vitro to diabetic rat models by intravitreal injection could reduce leakage of blood vessels and attenuate blood-retinal barrier breakdown induced by diabetes. (Chin J Ophthalmol, 2017, 53: 53-58).

[The normative values of vestibular evoked myogenic potentialin different age-groups]

Objective:To obtain the normative values of vestibular evoked myogenic potential(VEMP),i.e.the threshold,latency,latency-interval,amplitude of healthy population in Tianjin medical university General hospital.These values will help clinical diagnosis.Method:Seventy-five healthy individuals (39 males and 36 females,age from 21 to 70 years)were enrolled in this study.They were divided into 3 groups according to age:group 1(21-30 years),group 2(>30-50 years),group 3(>50-70 years).oVEMP and cVEMP were performed and the normative values were obtained.SPSS 19.0 was used to analyze the data.Result:The response rate was 77.3% and 85.3% of oVEMP and cVEMP respectively in all subjects.The values of oVEMP:in group 1 response rate was 100%,amplitude was(8.29±1.25)μV and threshold value was(83.65±4.10) dBnHL.In group 2 response rate was 85.4%,amplitude was(6.32±1.21)μV and threshold value was(89.24±4.18) dBnHL.In group 3 response rate was 46%,amplitude was(4.26±1.20) μV,threshold value was(95.13±4.21) dBnHL.The values of cVEMP: in group 1 response rate was 100%,amplitude was(108.87±19.10)μV and threshold value was(84.54±4.35) dBnHL.In group 2 response rate was 83.3%,amplitude was(84.10±20.02)μV and threshold value was (90.33±4.29)dBnHL.In group 3 response rate was 72.0%,amplitude was(64.18±19.22)μV and threshold value was (95.19±4.30)dBnHL.The statistical analysis show significant difference in oVEMP/cVEMP response rate,threshold and amplitude among different age-groups(P<0.05).No significant difference was found in N1,P1 latency and latency-interval among different age-groups(P>0.05).Conclusion:The normative values of VEMP of healthy population in Tianjin medical university General hospital were obtained in this research.These VEMP data were used for the diagnosis of related diseases.

Effect of different luteal support schemes on clinical outcome in frozen-thawed embryos transfer cycles

OBJECTIVE

To evaluate the clinical outcome of frozen-thawed embryo transfer (FET) when using different luteal support schemes.

STUDY DESIGN

Retrospective analysis of FET cycles was performed from June 2013 and December 2013. Infertile women, who underwent FET cycles utilizing embryos cryopreserved on day 3 post-insemination following an initial fresh IVF cycle. Patients were divided into three groups according to the luteal support scheme. Grade A (oral administration of progesterone, n=156), Group B (vaginal administration of progesterone, n=345), Group C (dissolved progesterone in oil with intramuscular infection, n=885), and group C was divided into two subgroups according to with (subgroup Cl, n=521) or without (subgroup C2 ,n=364) human chorionic gonadotrophi (hCG) injected intramuscularly. The authors compared patients' characteristics and the pregnancy outcomes of each group.

RESULTS

There was no difference in the patient characteristics of each group. There was no difference in the implantation rate or clinical and ongoing pregnancy rate among oral, vaginal, and intramuscular progesterone groups. The abortion and ectopic pregnancy rates were not significantly different among the three groups.

CONCLUSION

Oral progesterone in the FET cycles is convenient and has similar pregnancy outcomes compared with intramuscular or vaginal administration.

Shear stress regulates endothelial cell autophagy via redox regulation and Sirt1 expression

Disturbed cell autophagy is found in various cardiovascular disease conditions. Biomechanical stimuli induced by laminar blood flow have important protective actions against the development of various vascular diseases. However, the impacts and underlying mechanisms of shear stress on the autophagic process in vascular endothelial cells (ECs) are not entirely understood. Here we investigated the impacts of shear stress on autophagy in human vascular ECs. We found that shear stress induced by laminar flow, but not that by oscillatory or low-magnitude flow, promoted autophagy. Time-course analysis and flow cessation experiments confirmed that this effect was not a transient adaptive stress response but appeared to be a sustained physiological action. Flow had no effect on the mammalian target of rapamycin-ULK pathway, whereas it significantly upregulated Sirt1 expression. Inhibition of Sirt1 blunted shear stress-induced autophagy. Overexpression of wild-type Sirt1, but not the deacetylase-dead mutant, was sufficient to induce autophagy in ECs. Using both of gain- and loss-of-function experiments, we showed that Sirt1-dependent activation of FoxO1 was critical in mediating shear stress-induced autophagy. Shear stress also induced deacetylation of Atg5 and Atg7. Moreover, shear stress-induced Sirt1 expression and autophagy were redox dependent, whereas Sirt1 might act as a redox-sensitive transducer mediating reactive oxygen species-elicited autophagy. Functionally, we demonstrated that flow-conditioned cells are more resistant to oxidant-induced cell injury, and this cytoprotective effect was abolished after inhibition of autophagy. In summary, these results suggest that Sirt1-mediated autophagy in ECs may be a novel mechanism by which laminar flow produces its vascular-protective actions.

Parallel enzyme-linked immunosorbent assay screening for human immunodeficiency virus among blood donors in five Chinese blood centres: a retrospective analysis

AIMS

To evaluate the strategy of parallel screening with different enzyme-linked immunosorbent assays (ELISA) among Chinese blood donors.

BACKGROUND

Parallel screening with ELISA has been the main strategy to detect human immunodeficiency virus (HIV) in blood donations in China for more than a decade. The performance of the strategy should be analysed.

METHODS

A total of 821,927 donations collected from five Chinese blood centres in 2008-2010 were tested using two third-generation ELISAs by different manufacturers licenced and confirmed by the Western blot (WB) in this study. The confirmatory positive predictive values (PPV), false positive rates (FPR), false negative rates (FNR) and potential risks for transfusion resulting from single or sequential ELISA screening were evaluated.

RESULTS

A total of 5318 (0·647%) of donations screened HIV reactive and were discarded. WB confirmatory results on 1668 available samples suggested that PPVs for dual ELISA, one round ELISA reactive and grey zone samples were 75·1, 0·7 and 0·5%, respectively. Eight out of 1124 one round ELISA reactive and 1 out of 195 grey zone samples were WB confirmed positive. All but one ELISA assay displayed comparable PPVs but variable FPRs and FNRs that differed by blood centre.

CONCLUSIONS

In the absence of nucleic acid testing (NAT), parallel ELISA screening prevented a substantial number of HIV infected donations from entering the Chinese blood supply. However, the loss of false positive donors should be re-evaluated especially given the frequently reported blood supply shortage in China.

Two-year outcome of first-line antiretroviral therapy among HIV-1 vertically-infected children in Hanoi, Vietnam

A retrospective analysis of 86 HIV-1 vertically-infected Vietnamese children with a follow-up period >24 months after initiating antiretroviral therapy (ART) was performed from 2008 to 2012, to assess the outcome of first-line ART in resource-limited settings. Of the 86 children, 68 (79.1%) were treated successfully (plasma HIV-1 viral load [VL] <1000 copies/ml), and 63 (73.3%) had full viral suppression (VL <400 copies/ml) after 24 months of ART. No significant difference between successfully treated patients and failure groups was observed in VL, CD4(+) T-cell count or clinical stage at baseline; age at ART start; or ART regimen. All 14 children with VL >5000 copies/ml, one of four children with VL 1000-5000 copies/ml and none with VL <1000 copies/ml developed reverse transcriptase inhibitor (RTI)-resistance mutations by 24 months of ART. Y181C and M184V/I were the most dominant non-nucleoside and nucleoside RTI-resistance mutations, respectively (13/15, 86.7%). These findings suggest that VL testing after 24 months of ART can be used to efficiently differentiate ART failures among HIV-1 vertically-infected children in resource-limited settings.

Inhibition of farnesyl pyrophosphate synthase prevents angiotensin II-induced cardiac fibrosis in vitro

Farnesyl pyrophosphate synthase (FPPS)-catalysed isoprenoid intermediates are important for the activation of Ras homologue gene family, member A (RhoA) in angiotensin (Ang) II-induced cardiac fibrosis. This study was designed to investigate the specific role of FPPS in the development of cardiac fibrosis. We demonstrated that FPPS expression was elevated in both in-vivo and in-vitro models of Ang II-mediated cardiac fibrosis. FPPS inhibition by zolendronate and FPPS knock-down by a silencing lentivirus decreased the expression of cardiac fibrosis marker genes, including collagen I, collagen III and transforming growth factor (TGF)-β1. FPPS inhibition was reversed by geranylgeraniol (GGOH) and mimicked by RhoA knock-down with siRhoA. The antagonistic effect of GGOH on the zolendronate-mediated modulation of RhoA activation in Ang II-stimulated cardiac fibroblasts was demonstrated by a pull-down assay. Furthermore, FPPS knock-down also prevented RhoA activation by Ang II in vitro. In conclusion, FPPS and RhoA may be part of a signalling pathway that plays an important role in Ang II-induced cardiac fibrosis in vitro.