Systematic evaluation of SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.

OBJECTIVE: The COVID-19 pandemic poses an immense need for accurate, sensitive and high-throughput clinical tests, and serological assays are needed for both overarching epidemiological studies and evaluating vaccines. Here, we present the development and validation of a high-throughput multiplex bead-based serological assay. METHODS: More than 100 representations of SARS-CoV-2 proteins were included for initial evaluation, including antigens produced in bacterial and mammalian hosts as well as synthetic peptides. The five best-performing antigens, three representing the spike glycoprotein and two representing the nucleocapsid protein, were further evaluated for detection of IgG antibodies in samples from 331 COVID-19 patients and convalescents, and in 2090 negative controls sampled before 2020. RESULTS: Three antigens were finally selected, represented by a soluble trimeric form and the S1-domain of the spike glycoprotein as well as by the C-terminal domain of the nucleocapsid. The sensitivity for these three antigens individually was found to be 99.7%, 99.1% and 99.7%, and the specificity was found to be 98.1%, 98.7% and 95.7%. The best assay performance was although achieved when utilising two antigens in combination, enabling a sensitivity of up to 99.7% combined with a specificity of 100%. Requiring any two of the three antigens resulted in a sensitivity of 99.7% and a specificity of 99.4%. CONCLUSION: These observations demonstrate that a serological test based on a combination of several SARS-CoV-2 antigens enables a highly specific and sensitive multiplex serological COVID-19 assay.

Anti-Vibrio Indole-Diterpenoids and C-25 Epimeric Steroids From the Marine-Derived Fungus Penicillium janthinellum.

A systematic chemical exploration of the marine-derived fungus Penicillium janthinellum led to the isolation of four indole-diterpenoid derivatives (1-4), including new penijanthines C and D (1 and 2), and a pair of new steroidal epimers, penijanthoids A and B (5 and 6). The calculated ECD spectra and Snatzke's method for the new compound 1 were carried out to determine its absolute configuration. The absolute configuration of 3 was established by X-ray diffraction and calculated ECD methods for the first time. DP4plus approach was used to elucidate the absolute configurations of the C-25 epimeric steroids 5 and 6. 25-Epimeric 5 and 6 represent the first examples of steroids forming a five-membered lactone between C-23 and C-27 from marine fungi. Compounds 1, 2, 5, and 6 displayed significant anti-Vibrio activity (Minimum inhibitory concentration, MIC values ranging from 3.1 to 50.0 µM) against three pathogenic Vibrio spp.

Four new antitumor metabolites isolated from a mutant 3-f-31 strain derived from Penicillium purpurogenum G59.

Penicimutanolones A (1) and B (2), penicimutanolone A methyl ether (3), and penicimumide (4), four new antitumor metabolites, were isolated from a neomycin-resistant mutant of the marine-derived fungus Penicillium purpurogenum G59. The structures of the compounds were elucidated by spectroscopic methods, and the absolute configurations were determined by X-ray crystallography and calculated ECD. In MTT and SRB assays, compounds 1-3 showed strong inhibitory effects on 14 human cancer cell lines. Compounds 1 and 2 maybe induce apoptosis of cancer cells mainly due to the inhibition of the expression of survivin, a client protein of HSP90. In addition, in vivo antitumor activity was observed for compound 1 in murine sarcoma HCT116 tumor-bearing Kunming mice, using docetaxel as a positive control.

Perylenetetracarboxylic acid and carbon quantum dots assembled synergistic electrochemiluminescence nanomaterial for ultra-sensitive carcinoembryonic antigen detection.

It is important to design a nice electrochemiluminescence (ECL) biological nanomaterial for fabricating sensitive ECL immunosensor to detect tumor markers. Most reported ECL nanomaterial was decorated by a number of mono-luminophore. Here, we report a novel ECL nanomaterial assembled by dual luminophores perylenetetracarboxylic acid (PTCA) and carbon quantum dots (CQDs). In the ECL nanomaterial, graphene was chosen as nanocarrier. Significant ECL intensity increases are seen in the ECL nanomaterial, which was interpreted with the proposed synergistic promotion ECL meachanism of PTCA and CQDs. Furthermore, this ECL nanomaterial was used to label secondary antibody and fabricate a sandwiched carcinoembryonic antigen (CEA) immunosensor. The CEA immunosensor exhibits high sensitivity and the linear semilogarithmical range was from 0.001fgmL-1 to 1ngmL-1 with low detection limit 0.00026fgmL-1. And the CEA immunosensor is also suitable for various cancers' sample detection providing potential specific applications in diagnostics.

Single-mode interface states in heterostructure waveguides with Bragg and non-Bragg gaps.

Interface states can always arise in heterostructures that consist of two or more (artificial) materials with topologically different energy bands. The gapped band structure can be classified by the Chern number (a topological invariant) generally or the Zak phase in one-dimensional periodic systems. Recently, topological properties have been employed to investigate the interface states occurring at the connecting regions of the heterostructures of mechanical isostatic lattices and acoustical waveguides. Here, we study this heterostructure phenomenon by carefully connecting two corrugated stainless steel waveguides with Bragg and non-Bragg gaps at approximately the same frequency. These two waveguide structures can be achieved by continuously varying their geometry parameters when a topological transition exists in the forbidden bands, in which the reflection impedance changes the sign. Furthermore, a localized single high-order mode has been observed at the interface because of the transverse mode interactions, which relate to the non-Bragg gaps created by the different transverse mode resonances. Such a localized acoustic single mode with very large enhanced intensity could find its applications in sound detection, biomedical imaging, and underwater sound control, and could also enrich our means of wave front manipulations in various engineering fields.

Bioactive phenyl ether derivatives from the marine-derived fungus Aspergillus carneus.

A new phenyl ether derivative, 3-hydroxy-5-(3-hydroxy-5-methylphenoxy)-4-methoxybenzoic acid (1), along with two known analogues, 3,4-dihydroxy-5-(3-hydroxy-5-methylphenoxy)benzoic acid (2) and 3-hydroxy-5-(3-hydroxy-5-methylphenoxy)benzoic acid (3), were isolated from the fungus Aspergillus carneus collected from South China Sea. The structure elucidation of 1 was determined based on extensive NMR and MS spectroscopic analyses. Compound 2 showed a strong antioxidant activity with an IC50 value of 19.3 µM which was close to the positive control ascorbic acid (IC50 = 15.3 µM).

Usefulness of procalcitonin in elderly patients with bacterial infection.

BACKGROUND: The role of PCT (procalcitonin) in elderly patients with bacterial infection has not fully been investigated. In previous studies, the role of PCT in diagnosing bacterial infection has mainly been studied in patients with severe infections. This study was to access a diagnostic value of PCT in elderly patients with local infection. METHODS: A total of 259 elderly patients were enrolled in this study. Serum concentration of PCT and whole blood concentration of CRP was measured by immunofluorescence assay. RESULTS: The concentration of PCT was significantly higher in patients with infection than those without. In predicting bacterial infection, with a PCT cutoff value of 0.055 ng/mL, the specificity and sensitivity were 92.4% and 63.6%, respectively, while the specificity and sensitivity was 80.0% and 81.3% with a CRP cutoff value of 10.96 mg/L. The areas under the receiver operating characteristic curves (ROC-AUCs) of PCT and CRP were 0.792 and 0.858, respectively (p < 0.05). CONCLUSIONS: PCT may not be a better predictor than CRP for diagnosing bacterial infection in elderly patients, but its high specificity is helpful to rule in a bacterial infection.

[Raman spectra and structure analysis of 2,6-pyridine dicarboxylic acid in different states and single Bacillus spore].

The Raman spectra of 2,6-pyridine dicarboxylic acid (DPA) and their calcium salts(Ca-DPA) in different states and the Ca-DPA in a single bacterial spore have been recorded by laser tweezers Raman system (LTRS) and the spectra have been assigned. Raman spectra of different states of DPA and Ca-DPA are different evidently. Analysis leading to differences in the structure of spectrum may be due to that the Raman spectra of DPA crystalline reflected more precise characteristics information compared to DPA powder, in which the laser can penetrate through DPA crystalline and the Raman scatter from the crystalline interior is greater than that from DPA powder. The second reason is that DPA powder and Ca-DPA crystalline contain water molecules, and the intermolecular hydrogen bonding in the crystals of these molecules is extensive. The presence of calcium ions would affect the pyridine ring so that both sides of the carboxyl pyridine ring have a certain geometric deformation and the hydroxy carboxylic was damaged. The DPA2-anion is principal in Ca-DPA and the DPA solution. The calcium ion affects the stability of the pyridine ring structure in the Ca-DPA solution. The result from the spectra also showed that the DPA in single spores present Ca-DPA crystal state.

[Probing the mechanism and Ca-DPA concentration of individual Bacillus spores using trapping and Raman spectroscopy].

Measuring the levels of 2,6-pyridine dicarboxylic acid (DPA) in bacteria spores could provide the information about the DPA function, resistance mechanism and the mechanism of spore germination. The authors have measured levels of Ca-DPA of individual spores of different 19 kinds of Bacillus which from different sources, species, and strains by using laser tweezers Raman spectroscopy (LTRS). Also we have verified the reproducibility of the system simultaneously. To investigate the biochemical components and structure in single spore, a Raman tweezers setup was used to record the Raman spectrum of single spore. A NIR laser beam (30 mW, 785 nm) was introduced into an inverted microscope to form a tweezers for trapping the spore suspended in water, and the Raman scatter was excited by the same beam. Raman spectra of 30 spores of 19 bacillus strains which collected from different area in China were recorded, and 100 spores of B. subtilis ACCC10243 were measured. A spore of the same strain was probed 100 times for verifying the reproducibility of the LTRS system. A Matlab 7.0 edited program and Origin 8.0 were used to process the spectral data. Because Ca-DPA is the chelate of DPA and the calcium ion, and the strongest Raman bands at 1 017 cm(-1) was from Ca-DPA component of the spore, its intensity was linearly with the Ca-DPA concentration. Therefore, the 1017 cm(-1) bands of Ca-DPA could be used as the quantitative standard peak, and then calculated the concentration of Ca-DPA could be calculated according the intensity of 1017 cm(-1) peak. The results showed that Raman spectra of single spore can reflect the characteristics information of it. The diversity of Ca-DPA levels not only happened between different species and strains of bacillus, but also happened between different individual spores in the same strains of bacillus. Conclusion from these measurements is that there is heterogeneity in different individual spores. It is convenient to trapping and collecting its Raman spectrum in water directly, and then get the information of the level of DPA, without the complex preparation of separating, purifying spores and abstracting DPA, so we predict LTRS as a high sensitivity, high accuracy, rapid and effective method in the research of individual spores.

[Determination of two saponins in Tupistra chinensis rhizomes by RP-HPLC].

OBJECTIVE: To develog an HPLC method determination of two new saponins in the dried rhizomes of Tupistra chinensis. METHOD: The analysis was performed on YMC-Pack ODS-AQ (4.6 mm x 250 mm, 5 microm) eluted with of acetonitrile and waterin gradient mode. The conentration of acetonitrile in the mobile phase changes from 10% to 100% within 85 minutes. The detection wavelength was set at 203 nm. The flow rate was 1.00 mL x min(-1) and column temperature was set at 30 degrees C. RESULT: The linear relationships of two authentic saponins were determined within the range from 7.55 microg to 60.40 microg (r=0.9996) and 8.00 microg to 48.00 microg (r=0.9996), respectively. Using the method above, the contents of two saponins were determined as 0.261% and 0.242%, with the recoveries as 98.6% and 98.3% with RSD 1.7% and 1.7%, respectively. CONCLUSION: A convenient and reliable method was developed to determine the content of two saponins in the dried rhizomes of Tupistra chinensis.

New polyhydroxylated furostanol saponins with inhibitory action against NO production from Tupistra chinensis rhizomes.

Two furostanol saponins were obtained from the rhizomes of Tupistra chinensis Bak. Their structures were determined as 5beta-furost-delta(25(27))-en-1beta,2beta,3beta,4beta,5beta,7alpha,22xi,26-octaol-6-one-26-O-beta-D-glucopyranoside (1) and 5beta-furost-delta(25(27))-en-1beta,2beta,3beta,4beta,5beta,6beta,7alpha,22xi,26-nonaol-26-O-beta-D-glucopyranoside (2), on the basis of chemical and spectroscopic evidence. Both compounds displayed marked inhibitory action against NO production in rat abdomen macrophages induced by lipopolysaccharide (LPS) at 40 microg/mL.