Bacteria and viruses and clinical outcomes of asthma-bronchiectasis overlap syndrome: A cohort study.

BACKGROUND: Despite the high prevalence of co-existing bronchiectasis and asthma (asthma-bronchiectasis overlap syndrome [ABOS]), little is known regarding the dominant pathogens and clinical correlates. OBJECTIVE: To investigate the bacteria and viruses which differentially dominate in ABOS (including its subtypes) compared with bronchiectasis alone, and determine their relevance with bronchiectasis severity and exacerbations. METHODS: This was a prospective observational cohort study conducted between March 2017 and August 2023. We included 81 patients with ABOS and 107 patients with bronchiectasis alone. At steady-state baseline, patients underwent comprehensive assessments and sputum collection for bacterial culture and viral detection (quantitative polymerase-chain-reaction). Patients were followed-up to record exacerbation and spirometry. RESULTS: Patients with ABOS had significantly higher symptom burden and exacerbation frequency than those with bronchiectasis alone. Despite similar pathogen spectrum, the rate of bacteria-virus co-detection increased less substantially at acute exacerbations (AE) onset than at steady-state compared with bronchiectasis alone. Pathogenic bacteria (particularly Pseudomonas aeruginosa) were detected fairly common (exceeding 50%) in ABOS and were associated with greater severity of bronchiectasis when stable and conferred greater exacerbation risks at follow-up. Viral but not bacterial compositions changed substantially at AE onset compared with clinical stability. Higher blood eosinophil count, moderate-to-severe bronchiectasis and non-atopy were associated with higher odds of bacterial, but not viral, detection (all p < 0.05). CONCLUSION: Detection of bacteria or virus is associated with bronchiectasis severity or clinical outcomes in ABOS. This highlights the importance of integrating sputum microbial assessment for ascertaining the dominant pathophysiology (atopy vs. infection) and longitudinal trajectory prediction in ABOS.

A signal amplification for Trp isomers electrochemical recognition based on PEDOT:PSS and CS/PAA multilayers.

In this work, enhanced tryptophan (Trp) isomers recognition was successfully demonstrated on (CS/PAA)3.5@PEDOT:PSS/GCE, a multilayer chiral sensor with good stability and reproducibility. The (CS/PAA)n multilayers chiral interface was first fabricated via alternating self-assembly of chiral chitosan (CS) and achiral polyacrylic acid (PAA). Conductive PEDOT:PSS was then compounded with (CS/PAA)n multilayers to obtain the chiral sensor for the electrochemical recognition of Trp isomers. The structure of the sensor and its chirality properties for Trp isomers were characterized by fourier transform infrared spectroscopy (FT-IR)，scanning electron microscopy (SEM) and electrochemical methods. The SEM images showed uniform distribution of PEDOT:PSS in the multilayer films, which changed the internal structure of the (CS/PAA)3.5. Consequently, (CS/PAA)3.5@PEDOT:PSS multilayers rendered more chiral centers in addition to improved good conductivity, which significantly amplified the oxidation peak current ratio of D-Trp to L-Trp (ID/IL) up to 6.71 at 25 °C. In addition, a linear relationship was observed between the peak current and Trp enantiomer concentration in the range of 0.002-0.15 mM, and the detection limits of D-Trp and L-Trp were 0.33 and 0.67 µM, respectively. More importantly, the percentage of D-Trp in non-racemic Trp enantiomers mixture solutions were successfully determined on the chiral interface, showing its effectiveness and promising potential in practical applications.

Total alkaloid fraction of Leonurus japonicus Houtt. Promotes angiogenesis and wound healing through SRC/MEK/ERK signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Leonurus japonicus Houtt., also known as motherwort, is a traditional Chinese medicine that was first identified in Shennong Bencao Jing, the first and essential pharmacy monograph in China. L. japonicus has been regarded as a good gynecological medicine since ancient times. It has been widely used in clinical settings for treatment of gynecological diseases and postnatal rehabilitation with good efficacy and low adverse effects. AIM OF THE STUDY: The main purpose of this study was to determine the angiogenic and wound healing effects of total alkaloid fraction from L. japonicus Houtt. (TALH) in vivo and in vitro. In addition, the main bioactive components of total alkaloids were to be identified and analyzed in this study. MATERIALS AND METHODS: First, the UHPLC/Q-TOF-MS method was used to identify and quantify the major components in the TALH extract. The wound healing activity was evaluated in vivo using a rat full-thickness cutaneous wound model. Histological study of wound healing in rat model was performed via immunohistochemistry and immunofluorescence. Cell proliferation was determined by MTT assay. Wound healing and transwell assays were used for detection of cell migration. The effect on tube formation was determined by tube formation assay in HUVECs. Western blot and RT-PCR were used to detect the expressions of relative proteins and genes respectively. Knock-down of SRC by siRNA was done to verify the crucial role of SRC in promotion of angiogenesis induced by TALH. RESULTS: Seven characteristic peaks were recognized in the UHPLC/Q-TOF-MS spectrum, while four of the main components were quantified. The wound model in rats showed that treatment of TALH promoted wound healing by stimulating cellular proliferation and collagen deposition. In vitro experiments showed that co-treatment of TALH and VEGF increased cell proliferation, migration and tube formation in HUVECs. Mechanistic studies suggested that the co-treatment increased gene expressions of SRC, MEK1/2 and ERK1/2, as well as the phosphorylation levels of these proteins. Furthermore, the effect of co-treatment was attenuated after SRC knockdown, suggesting that SRC plays an important role in angiogenesis and wound healing induced by TALH and VEGF co-treatment. CONCLUSION: Our results showed that TALH was one of the main active components of L. japonicus that promoted angiogenesis and wound healing by regulating the SRC/MEK/ERK pathway. Our study provided scientific basis for better clinical application of L. japonicas.

High platelet count predicts poor prognosis in HCC patients undergoing TACE: a propensity score-matched analysis.

BACKGROUND: The aim of this study was to retrospectively evaluate the prognostic value of the pretreatment platelet (PLT) count in patients with hepatitis B virus (HBV)-related intermediate-advanced hepatocellular carcinoma (HCC) complicated with cirrhosis undergoing transcatheter arterial chemoembolization (TACE). RESEARCH DESIGN AND METHODS: We assessed 362 patients with HBV-related intermediate-advanced HCC complicated with cirrhosis undergoing TACE. Patients were divided into low (≤96 × 109/L) and high (>96 × 109/L) PLT groups. Propensity score matching (PSM) was performed to eliminate the imbalance in potential confounding factors. The endpoint was time to progression (TTP). RESULTS: After PSM, the high and low PLT groups had 97 patients each. The TTP was significantly longer in the low PLT group than in the high PLT group (log-rank test, p < 0.001). A high pretreatment PLT count was an independent predictor of poor tumor response (OR 4.724; 95% CI 1.889-11.815; P = 0.001) and short TTP (HR = 3.598; 95% CI: 2.570-5.036; P < 0.001). Subgroup analysis showed that a high PLT count increased the risk of progression across almost all subgroups. CONCLUSIONS: The pretreatment PLT count has potential value in predicting the prognosis of patients with intermediate-advanced HCC undergoing TACE.

Physicians' perceptions of generic drugs in China.

Background: In recent years, there has been a significant worldwide increase in the use of generic drugs. China has committed to a consistency evaluation of generic drugs, with the aim to improve the rate of substitution. However, there is little research on physicians' perceptions of generic drugs in China. Objective: The study aimed to explore the perceptions of physicians in China toward generic drugs. Methods: Perceptions of Chinese physicians towards generic drugs were evaluated by a cross-sectional study from June to July 2020. The online survey tool Sojump was adopted to distribute the questionnaires using convenience sampling. A total of 598 questionnaires were analyzed. Results: Perceptions of Chinese physicians towards generic drugs are generally positive. However, not all physicians appear to have sufficient knowledge about generic drugs and some of them expressed negative perceptions of generic drugs, such as perceiving generic drugs as less effective and more likely to cause side effects compared to brand-name drugs. There were significant differences in physicians' opinions about generic drugs according to age group, years in practice, educational background, clinical specialty and residential area. Conclusion: It is imperative to provide physicians with more extensive education about the consistency evaluation of generic drugs to meet the policy goal of reducing overall national medical healthcare costs.

Highly Sensitive Detection of miR-21 through Target-Activated Catalytic Hairpin Assembly of X-Shaped DNA Nanostructures.

MicroRNAs (miRNAs) are found in extremely low concentrations in cells, so highly sensitive quantitation is a great challenge. Herein, a simple dual-amplification strategy involving target-activated catalytic hairpin assembly (CHA) coupled with multiple fluorophores concentrated on one X-shaped DNA is reported. In this strategy, four hairpin probes (H1, H2, H3, and H4) are modified with FAM and BHQ1 at both sticky ends, while a circulating hairpin probe (H0) is used to activate CHA circuits once it binds to complementary sequences in the target miR-21 (T). The powerful dual-amplification cascades in Förster resonance energy transfer (FRET)-based nonenzymatic nucleic acid circuits are triggered by T-H0-activated formation of the X-shaped DNA nanostructure, freeing T-H0 for the next CHA reaction cycle. CHA circuits increase the fluorescence due to the wide distance between FAM and BHQ1 in the formed X-shaped DNA nanostructure, resulting in signal amplification and highly sensitive detection of miR-21, with a limit of detection (LOD, 3σ) of 0.025 nM, which is 25.6 or 57.6 times lower than that obtained through a single-amplification strategy without multiple fluorophores on one X-shaped DNA or CHA circuit. Furthermore, this cascade reaction was completed in 45 min, effectively avoiding target degradation. This new enzyme-free signal amplification strategy holds promising potential for sensitively detecting different DNA or RNA sequences by simply adapting the fragment of the H0 sequence complementary to the target.

The different correlations between obesity and osteoporosis after adjustment of static mechanical loading from weight and fat free mass.

OBJECTIVES: To explore complex correlations between obesity (OB) and osteoporosis (OP) after adjustment of static mechanical loading from weight and fat free mass (FFM). METHODS: A total of 3749 Chinese aged ≥65 years were selected from our ongoing cohort study. OB indices and bone mineral density (BMD) were measured for each subject. Linear regression analyses were performed to explore the correlations between OB indices and OP under three adjustment models (unadjusted, adjusted with weight and adjusted with FFM). RESULTS: Under no adjustment, three general obesity indices (body mass index: BMI, fat mass: FM, and percentage FM: PFM) were positively associated with BMD at three skeletal sites (P<0.001) in the regression analyses. However, after the adjustment with weight, these associations were mostly significant but reverse i.e., negatively in direction. After adjustment with FFM, the three indices were still positively and significantly (P<0.001) associated with BMD but regression coefficients were smaller compared to the unadjusted associations. Similar associations were observed for central adiposity and lower limb adiposity indices. CONCLUSIONS: The combined relation of OB to OP due to the physiological factors secreted from adipose tissues and the static mechanical loading from FM is positive in direction.

Differential and paradoxical roles of new-generation antidepressants in primary astrocytic inflammation.

BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are commonly used new-generation drugs for depression. Depressive symptoms are thought to be closely related to neuroinflammation. In this study, we used up-to-date protocols of culture and stimulation and aimed to understand how astrocytes respond to the antidepressants. METHODS: Primary astrocytes were isolated and cultured using neurobasal-based serum-free medium. The cells were treated with a cytokine mixture comprising complement component 1q, tumor necrosis factor α, and interleukin 1α with or without pretreatments of antidepressants. Cell viability, phenotypes, inflammatory responses, and the underlying mechanisms were analyzed. RESULTS: All the SSRIs, including paroxetine, fluoxetine, sertraline, citalopram, and fluvoxamine, show a visible cytotoxicity within the range of applied doses, and a paradoxical effect on astrocytic inflammatory responses as manifested by the promotion of inducible nitric oxide synthase (iNOS) and/or nitric oxide (NO) and the inhibition of interleukin 6 (IL-6) and/or interleukin 1ß (IL-1ß). The SNRI venlafaxine was the least toxic to astrocytes and inhibited the production of IL-6 and IL-1ß but with no impact on iNOS and NO. All the drugs had no regulation on the polarization of astrocytic A1 and A2 types. Mechanisms associated with the antidepressants in astrocytic inflammation route via inhibition of JNK1 activation and STAT3 basal activity. CONCLUSIONS: The study demonstrated that the antidepressants possess differential cytotoxicity to astrocytes and function differently, also paradoxically for the SSRIs, to astrocytic inflammation. Our results provide novel pieces into understanding the differential efficacy and tolerability of the antidepressants in treating patients in the context of astrocytes.

Carbon dots-based fluorescence resonance energy transfer for the prostate specific antigen (PSA) with high sensitivity.

The accurate and sensitive detection of biomarkers has great clinical value for the early diagnosis and treatment of cancer. Due to the excellent optical properties of carbon dots (CDs), CDs-based fluorescent detection methods have attracted increasing attention in bioanalytics. Signal reporters using CDs labeled hairpin DNA, based on Föster resonance energy transfer (FRET), have shown promise for the sensitive detection of biomarkers. In this work, a new method for sensitive biomarker detection using an enzyme-free amplified fluorescence strategy was developed. The strategy was based on FRET between CDs and graphene oxide (GO) combined with catalytic hairpin assembly (CHA). In the absence of the target, the CD-labeled hairpin DNA adsorb onto GO via hydrophobic and π-π stacking interactions, resulting in a FRET quenching of the CDs fluorescence. The introduction of the target could trigger the CHA circuits to form Y-shaped double-stranded DNA (dsDNA), resulting in a recovery of the CD's fluorescence signal. This novel strategy was successfully applied for the selective detection of prostate specific antigen (PSA) with a limit of detection (LOD) of 0.22 ng mL-1 (3σ/k). Additionally, the method could be used to detect carcinoembryonic antigen (CEA) and adenosine triphosphate (ATP) with LOD of 0.56 ng mL-1 (3σ/k) and 80 nM (3σ/k), respectively. Therefore, this work demonstrates a promising way to construct a sensitive and versatile detection platform.

Paroxetine suppresses reactive microglia-mediated but not lipopolysaccharide-induced inflammatory responses in primary astrocytes.

BACKGROUND: Astrocytes are the most abundant glial cells in a brain that mediate inflammatory responses and provide trophic support for neurons. We have previously disclosed that paroxetine, a common selective serotonin reuptake inhibitor, ameliorates LPS-induced microglia activation. However, it remains elusive for the role of paroxetine in astrocytic responses. METHODS: Isolated primary astrocytes were pretreated with paroxetine and stimulated with different stimuli, lipopolysaccharide (LPS) or microglia conditioned medium pre-activated with LPS (M/Lps). Inflammatory and neurotrophic responses, underlying mechanisms and the impact on neuronal survival were assessed. RESULTS: Paroxetine had no impact on LPS-stimulated iNOS, TNF-α, and IL-1ß expression, but inhibited M/Lps-induced TNF-α and IL-1ß expression in primary astrocytes. Paroxetine suppressed M/Lps- but not LPS-induced activation of NF-κB and had no impact on the activation of MAPKs and STAT3. Incubation with the resulted astrocyte conditioned media caused no change in the viability of SH-SY5Y cells. BDNF and MANF mRNA expressions were upregulated by M/Lps and paroxetine, respectively. However, M/Lps- or LPS-induced extracellular releases of NO, TNF-α, and/or BDNF in astrocytes were in minor amount compared to those by microglia. CONCLUSIONS: Paroxetine ameliorates the reactive microglia-mediated inflammatory responses in astrocytes partially via inhibition of the NF-κB pathway but has no impact on LPS-stimulated astrocyte activation. While the effects of paroxetine on secondary astrocytic responses are not robust compared to its effect on the innate immune responses of microglia, the results together may implicate a therapeutic potential of paroxetine against neuroinflammation-associated neurological disorders such as Parkinson's disease.

Polarity-Sensitive Polymer Carbon Dots Prepared at Room-Temperature for Monitoring the Cell Polarity Dynamics during Autophagy.

Taking the advantages of excellent optical properties, biocompatibility, and photostability of carbon dots, herein, we developed polarity-sensitive polymer carbon dots (PCDs) for visualizing of cellular polarity to real-time monitoring autophagy changes without perturbing the cellular status. The PCDs can be prepared by simply mixing dopamine (DA), H2O2, and o-phenylenediamine (o-PDA) in a common beaker without the need for any special equipment or external energy supply, and the preparation could be completed within 3 min at room temperature. Interestingly, the polarity-sensitive PCDs could emit various types of fluorescence and are insensitive to the excitation light when dispersed in different water/dioxane systems with different polarities. Based on the polarity-sensitive emission of the PCDs, the change of polarity during autophagy has been successfully monitored in living cells. Moreover, the change of polarity detected by PCDs is autophagy-specific (does not occur during apoptosis), occurs under different autophagy-inducing situations (starvation, rapamycin, and trehalose), and requires a normal autophagic flux, showing that PCDs rapidly prepared by polymerization cross-linking at room temperature can be functionally applied in the case of autophagy-related physiological or pathological processes.

A mimetic peptide of α2,6-sialyllactose promotes neuritogenesis.

Oxidative stress contributes to the pathogenesis of neurodegenerative diseases. With the aim to find reagents that reduce oxidative stress, a phage display library was screened for peptides mimicking α2,6-sialyllactose (6'-SL), which is known to beneficially influence neural functions. Using Sambucus nigra lectin, which specifically binds to 6'-SL, we screened a phage display library and found a peptide comprising identical sequences of 12 amino acids. Mimetic peptide, reverse peptide and scrambled peptide were tested for inhibition of 6'-SL binding to the lectin. Indeed, lectin binding to 6'-SL was inhibited by the most frequently identified mimetic peptide, but not by the reverse or scrambled peptides, showing that this peptide mimics 6'-SL. Functionally, mimetic peptide, but not the reverse or scrambled peptides, increased viability and expression of neural cell adhesion molecule L1 in SK-N-SH human neuroblastoma cells, and promoted survival and neurite outgrowth of cultured mouse cerebellar granule neurons challenged by H2O2-induced oxidative stress. The combined results indicate that the 6'-SL mimetic peptide promotes neuronal survival and neuritogenesis, thus raising hopes for the treatment of neurodegenerative diseases. This study was approved by the Medical Ethics Committee of Shantou University Medical College, China (approval No. SUMC 2014-004) on February 20, 2014.

Dual Energy Transfer-Based Fluorescent Nanoprobe for Imaging miR-21 in Nonalcoholic Fatty Liver Cells with Low Background.

Nonalcoholic fatty liver disease (NAFLD) can progress gradually to liver failure, early warning of which is critical for improving the cure rate of NAFLD. In situ imaging and monitoring of overexpressed miR-21 is an advanced strategy for NAFLD diagnosis. However, this strategy usually suffers from the high background imaging in living cells owing to the complexity of the biological system. To overcome this problem, herein, we have developed a one-donor-two-acceptor nanoprobe by assembling gold nanoparticles (AuNPs) coupled with BHQ2 (AuBHQ) and quantum dots (QDs) through DNA hybridization for imaging of miR-21 in living cells. The fluorescence of QDs was quenched up to 82.8% simultaneously by the AuNPs and the BHQ2 via nanometal surface energy transfer and fluorescence resonance energy transfer, reducing the background signals for target imaging. This low background fluorescent nanoprobe was successfully applied for imaging the target miR-21 in nonalcoholic fatty liver cells by catalyzing the disassembly of QDs with the AuBHQ and the fluorescence recovery of QDs. In addition, the sensitivity of this nanoprobe has also been enhanced toward detecting miR-21 in the range of 2.0-15.0 nM with the detection limit (LOD, 3σ) of 0.22 nM, which was 13.5 times lower than that without BHQ2. The proposed approach provides a new way for early warning, treatments, and prognosis of NAFLD.

SLC6A4 Repeat and Single-Nucleotide Polymorphisms Are Associated With Depression and Rest Tremor in Parkinson's Disease: An Exploratory Study.

Introduction: Level of serotonin is mainly regulated by the serotonin reuptake transporter encoded by SLC6A4. The promoter region of SLC6A4 bears a repeat polymorphism 5-HTTLPR and a single nucleotide polymorphism rs25531. We have previously studied the association between these two variants and sporadic PD. The objective of the current study was to determine whether the SLC6A4 polymorphisms were associated with key motor and non-motor symptoms of PD. Methods: A total of 370 PD patients of Han Chinese were included. Associations between the SLC6A4 polymorphisms and PD symptoms including depression, intellectual impairment, tremor and rigidity were analyzed. Results: 5-HTTLPR was associated with depression in PD patients and presence of the LL genotype was protective against the depression risk. The rs25531 was associated with rest tremor in PD and the A allele serves as a recessive risk allele. No associations were found in the two polymorphisms with respect to intellectual impairment and rigidity in the cohort. Conclusion: The current study reveals two PD symptoms associated with SLC6A4 polymorphisms, and provides new insight into how serotonergic system genetically participates in the symptomatic progression of PD. Further study is warranted in additional populations.

Dy(III)-induced aggregation emission quenching effect of single-layered graphene quantum dots for selective detection of phosphate in the artificial wetlands.

Carbon quantum dots (CQDs), prepared by one-step hydrothermal treatment of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and triethylamine (TEA), could be exfoliated or delaminated into single-layered graphene quantum dots (s-GQDs) with methanol for the first time, with fluorescence (FL) emission at 500 nm when excited at 417 nm. The s-GQDs, with more sufficient carboxyl groups on the surface than CQDs, could be induced to be aggregated by metal ion dysprosium (Dy3+), resulting in aggregation-induced emission quenching effect subsequently. However, the presence of phosphate (PO43-) destroys the Dy3+-induced aggregates of s-GQDs owing to the strong coordination between Dy3+ and PO43-, inducing the FL emission recovery of the s-GQDs and providing selective detection method of PO43- in the artificial wetlands with the linear range of 0.2-30 µM and determination limit of 0.1 µM (3σ).

Anthrax biomarker: An ultrasensitive fluorescent ratiometry of dipicolinic acid by using terbium(III)-modified carbon dots.

The highly sensitive detection of dipicolinic acid (DPA), a biomarker of the biological threat-agent anthrax, is strongly associated with the sensing of Bacillus anthracis (B. anthracis) in environmental and food samples. In this study, we developed a novel, ultrasensitive method for the detection of DPA by using a ratiometric fluorescent terbium ions modified carbon dots (CDs-Tb). The CDs-Tb showed two fluorescent emission bands at 459 nm and 495 nm when excited at the single wavelength of 260 nm. DPA could specifically bind with terbium ions on the surface of CDs through strong chelate-conjugation to produce antenna effect, resulting in significantly enhancement of the 495 nm emission peak without affecting the 459 nm emission peak. The fluorescence intensity ratio (I495/I459) of CDs-Tb was proportional to the concentration of DPA in the range of 0.5 nM to 2.5 µM with the limit of detection as low as 100 pM. This selective and ultrasensitive assay had a great application prospect in the complex matrixes owing to its simplicity and specificity for DPA. Meanwhile, the CDs-Tb-based paper sensor was successfully developed for sensitive and visual detection of DPA.

Functional preserving carbon dots-based fluorescent probe for mercury (II) ions sensing in herbal medicines via coordination and electron transfer.

Mercury ions (Hg2+) are one of the compulsory items in the quality control of herbal medicines for its serious toxicity to human health. Highly selective and sensitive Hg2+ detection, especially in complex real samples, is still challenging. In this work, Fluorescent (FL) carbon dots (CDs) with a core-shell structures composed of the crystalline core of stacked sp2-hybridized carbon layers and the shell of functional groups on the periphery of carbon layers are facilely prepared through a one-step hydrothermal synthetic route. They can specifically interact with Hg2+ in aqueous medium to form aggregates, during which coordination of carboxyl functional groups on the surface of CDs with Hg2+ occurred, which facilitated electron transfer from the CDs to Hg2+. As a result, fluorescence of the CDs was quenched with a high efficiency, making the detection of Hg2+ highly sensitive with the limit of determination (LOD) of 2.2 nM (3σ). With that, detection of Hg2+ in the complex compound herbal medicines samples with highly reproducible results has been successfully realized by using the as-prepared CDs, showing that fluorescent CDs-based probe may have great potential in the quality controls of heavy metals for pharmaceutical analysis.

Ratiometrically Fluorescent Electrospun Nanofibrous Film as a Cu2+-Mediated Solid-Phase Immunoassay Platform for Biomarkers.

Increasing demands for the sensitive, selective, visual, conveniently solid-phase-sensing film for disease-related biomarkers, electrospun nanofibrous films (ENFFs) are a novel sensing paltform because of the high surface area ratios, networked structures, and facile functionalization. In this research, carbon dots (CDs) and quantum dots (QDs) were doped inside and electrostatically assembled on electrospun nanofibers (ENFs), affording ratiometrically dual-emitting fluoresecent films. Because of the FRET process between CDs and QDs on NFs and the strong quenching response of QDs to Cu2+, the as-prepared NFs can visually detect Cu2+ with high sensitivity and selectivity based on ratiometric fluorescent signals. By exploiting the release of numerous Cu2+ from CuO nanoparticles (NPs) under acidic conditions, a sandwich-type immunoassay with CuO NPs-labeled antibody was developed for the detection of biomarker proteins via the response of dual-emitting and FRET-based NFs to different Cu2+ concentrations. Taking advantage of the ratiometrically fluorescent property of these ENFFs as well as the Cu2+-mediated signal amplification strategy, alpha fetoprotein can be detected with high sensitivity (detection limit of 8.3 pg/mL) and selectivity. This strategy demonstrates a promising candidate with a point-of-care assay for clinical diagnostics and biomedical research.

[Expression, purification and activity analysis of GGDEF and EAL domain-containing proteins from Lactobacillus acidophilus].

OBJECTIVE: To identify the functions of the proteins containing the GGDEF or EAL domain in Lactobacillus acidophilus for investigation of the regulatory mechanism of c-di-GMP in this strain. METHODS: The DNA fragments of NH13_07045-GGDEF, NH13_07050 and NH13_07055 from Lactobacillus acidophilus ATCC4356 were amplified by PCR and cloned into the expression vector pMAL-His-c2. After sequencing, the recombinant plasmids were transformed into competent Escherichia coli cells, which were induced by IPTG to express the recombinant proteins fused with maltose binding protein (MBP). The fusion proteins were purified using amylose resin column for diguanylate cyclase (DGC) or phosphodiesterase (PDE) activity assays in vitro followed by analysis with high-performance liquid chromatography (HPLC). RESULTS: The target DNA fragments were obtained by PCR, and their sequences were all identical to that in GenBank. The purified and concentrated fusion proteins, which were identified by SDS-PAGE and Western blotting, had relative molecular masses of 59 kD, 67 kD and 72 kD. HPLC analysis showed no DGC activity in NH13_07045-GGDEF, while PDE activity was found in NH13_07050 but not in NH13_07055. CONCLUSION: We obtained the protein encoded by NH13_07050 that possesses PDE activity in vitro. This protein may facilitate the evaluation of the regulatory function of c-di-GMP in Lactobacillus acidophilus.