Evaluation of reverse transcription loop-mediated isothermal amplification assay for the detection of severe fever with thrombocytopenia syndrome in clinical laboratories: A single-center study.

Severe fever with thrombocytopenia syndrome (SFTS) is an acute infectious disease prevalent in East Asia with a high mortality rate (5%-30%). Reverse transcription loop-mediated isothermal amplification (RT-LAMP), a rapid nucleic acid-based diagnostic technique, is a useful alternative for the clinical diagnosis of SFTS, particularly in resource-limited hospitals or rural clinics in SFTS virus-endemic regions. However, the actual clinical sensitivity and specificity of RT-LAMP remain unclear. This study evaluated the field application of RT-LAMP. This prospective field study included 130 patients with laboratory-confirmed SFTS from Yantai, Shandong Province, China. Two sets of RT-LAMP primers were validated, and one set of RT-LAMP assays was optimized for field detection. Nucleic acids of serially collected serum/plasma samples were identified using quantitative reverse transcription polymerase chain reaction (RT-qPCR) and RT-LAMP. In laboratory tests, we optimized the detection time of primer set 2 for the RT-LAMP to 60 min. Notably, the onsite testing of 279 plasma samples from patients with SFTS revealed that the sensitivity and specificity of the test were 81.9% and 96.3%, respectively. We also analyzed samples with different durations of the disease, and our study showed that the sensitivity of RT-LAMP detection at the beginning of admission was 89.92%. Univariate analysis showed that the detection rate of RT-LAMP was similar to that of RT-qPCR in the first 5 days of the disease course and was lower than that of RT-qPCR on Days 6 and 14-15 of the disease course. The positive detection rate in patients aged ≥ 65 years was significantly higher than that in younger age groups. RT-LAMP is a simple, suitable, and rapid clinical detection method of SFTS onsite screening. It is more suitable for screening patients in the early stages of the disease and analyzing samples obtained from patients aged ≥ 65 years before the 6th day of the disease course.

High-Performance Turn-On Fluorescent Metal-Organic Framework for Detecting Trace Water in Organic Solvents Based on the Excited-State Intramolecular Proton Transfer Mechanism.

Simple, fast, and sensitive detection of trace water in organic solvents is an urgent requirement for chemical industries. Herein, combining the unusual excited-state intramolecular proton transfer (ESIPT) mechanism with the effective strategy of pore space partition, for the first time, we construct a powerful fluorescent metal-organic framework (SNNU-301) probe with excellent water stability. The SNNU-301 probe shows a remarkable performance for turn-on ESIPT-based fluorescence response to water in nine common organic solvents, exhibiting wide linear ranges, low limit of detection values, and ultrafast response, especially in dimethyl sulfoxide (0-5.2%; 0.011%, v/v; 110 s). The typical ESIPT-sensitive linker 2,5-dihydroxyterephthalate (DHBDC) imparts it with discriminative detection properties via enol-keto tautomerism, and light-responsive triangular tri(pyridin-4-yl)-amine (TPA) realizes pore space partition. The theoretical calculation gives an in-depth explanation about the proton transfer mechanism. Comparative experiments and GCMC simulation provide evidence that the synergy of the ESIPT process and TPA of the framework further boosts its performance effectively. Definitely, this work not only offers a promising candidate with fast detection speed, high sensitivity, excellent universality, and visual observation for the determination of water in organic solvents but also provides valuable guidance for the design of high-performance fluorescent probes.

Safety of the 15-valent pneumococcal conjugate vaccine: A phase I clinical trial.

To evaluate the safety of the 15-valent pneumococcal conjugate vaccine (PCV15 (by LvZhu & Co. Ltd)) in healthy infants aged 2 months (minimum to 6 weeks) and 3 months old. This phase I clinical trial enrolled 80 subjects in Laishui County, Hebei Province, China. The total population was divided into 4 age groups on average: 20 adults (≥18 years) and 20 children (1-5 years) all received one vaccine dose; 20 infants (3 months) received the vaccine according to a 3-dose schedule at 0, 1, and 2 months. Twenty infants (2 months, minimum of 6 weeks old) received the vaccine according to a 3-dose schedule of 0, 2, and 4 months. The adverse events (AEs) until 30 days after each dose and serious adverse events (SAEs) until 6 months after the whole dose were reported. The solicited and unsolicited AE frequencies and laboratory indices were similar among the treatment groups. No vaccine-related SAEs were reported. Most vaccine-related adverse events consisting of systemic and local reactions were fever and pain. One hypersensitivity manifested as systemic urticaria that occurred on the third day after the second dose in the 2-month group. The 15-valent pneumococcal conjugate vaccine was generally well tolerated in infants.

Coinfections in hospitalized patients with severe fever with thrombocytopenia syndrome: A retrospective study.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease with a high case fatality rate. Few studies have been performed on bacterial or fungal coinfections or the effect of antibiotic therapy. A retrospective, observational study was performed to assess the prevalence of bacterial and fungal coinfections in patients hospitalized for SFTSV infection. The most commonly involved microorganisms and the effect of antimicrobial therapy were determined by the site and source of infection. A total of 1201 patients hospitalized with SFTSV infection were included; 359 (29.9%) had microbiologically confirmed infections, comprised of 292 with community-acquired infections (CAIs) and 67 with healthcare-associated infections (HAIs). Death was independently associated with HAIs, with a more significant effect than that observed for CAIs. For bacterial infections, only those acquired in hospitals were associated with fatal outcomes, while fungal infection, whether acquired in hospital or community, was related to an increased risk of fatal outcomes. The infections in the respiratory tract and bloodstream were associated with a higher risk of death than that in the urinary tract. Both antibiotic and antifungal treatments were associated with improved survival for CAIs, while for HAIs, only antibiotic therapy was related to improved survival, and no effect from antifungal therapy was observed. Early administration of glucocorticoids was associated with an increased risk of HAIs. The study provided novel clinical and epidemiological data and revealed risk factors, such as bacterial coinfections, fungal coinfections, infection sources, and treatment strategies associated with SFTS deaths/survival. This report might be helpful in curing SFTS and reducing fatal SFTS.

Correlations of FUT3 gene polymorphisms with colon polyps.

OBJECTIVE: To explore the relationship between fut3 gene polymorphism and colonic polyps. METHODS: Two hundred patients with colonic polyps and 200 healthy people in our hospital in recent 3 years were taken as the research objects, as the disease group and the control group, respectively. The disease group was divided into cancerous colonic polyps group (n = 50) and non-cancerous colonic polyps group (n = 150).    The peripheral blood nucleated cells of the subjects were collected and isolated. The fut3 gene polymorphism was obtained by sequencing and analyzed combined with the expression of fut3 gene and the level of tumor markers. RESULTS: The frequency of allele C at rs2561796 locus in the disease group was significantly higher than that in the control group (P < 0.05). The frequency of Ag genotype at rs441158 locus in the disease group was significantly higher than that in the control group, and the frequency of Ca genotype at rs2561796 locus was significantly lower than that in the control group (P < 0.05). In the disease group, the frequency of AA + Ag in the dominant model at rs441158 was significantly higher than that in the control group, and the frequency of Ca + AA in the invisible model at rs2561796 was significantly higher than that in the control group (P < 0.05). The frequency of CGC haplotype in the disease group was higher than that in the control group (P < 0.05). The linkage disequilibrium of rs441158 and rs2561796 loci of fut3 gene was high (d' = 0.423). The genotype of rs372725 of fut3 gene was correlated with the expression of fut3 gene (P < 0.05). The expression of fut3 gene in patients with CC genotype was significantly higher than that in patients with other genotypes (P < 0.05).   Conclusion: fut3 gene polymorphism is associated with the susceptibility and carcinogenesis of colonic polyps.

A New Molecular Recognition Concept: Multiple Hydrogen Bonds and Their Optically Triggered Proton Transfer in Confined Metal-Organic Frameworks for Superior Sensing Element.

We report a new sensing mechanism based on an indium-dihydroxyterephthalic acid metal-organic framework (MOF, SNNU-153), in which the spatially fitted analyte-MOF hydrogen-bond (H-bond) formation provides selective recognition while the analyte-H-bond assisted excited-state intramolecular proton transfer (ESIPT) and the resulting ratiometric emission act as a superior signal transducer with ultrafast response. The synergy of ESIPT signal transduction and confined MOF pore enables the SNNU-153 sensor selectively sensing hydrazine even among nitrogen-containing hydride analogs such as NH3, NH2OH, and (Me)2NNH2. The key of H-bond and associated ESIPT was further counter evidenced by an indium-2,5-dimethoxyterephthalic acid MOF (SNNU-152), where the hydroxyl protons were removed by methylation, showing near inertness to N2H4. The new molecular recognition concept thus makes SNNU-153 a powerful N2H4 sensor, which should be far-reaching to other sensing elements.

Characterization and Mechanistic Study of the Radical SAM Enzyme ArsS Involved in Arsenosugar Biosynthesis.

Arsenosugars are a group of arsenic-containing ribosides that are found predominantly in marine algae but also in terrestrial organisms. It has been proposed that arsenosugar biosynthesis involves a key intermediate 5'-deoxy-5'-dimethylarsinoyl-adenosine (DDMAA), but how DDMAA is produced remains elusive. Now, we report characterization of ArsS as a DDMAA synthase, which catalyzes a radical S-adenosylmethionine (SAM)-mediated alkylation (adenosylation) of dimethylarsenite (DMAsIII ) to produce DDMAA. This radical-mediated reaction is redox neutral, and multiple turnover can be achieved without external reductant. Phylogenomic and biochemical analyses revealed that DDMAA synthases are widespread in distinct bacterial phyla with similar catalytic efficiencies; these enzymes likely originated from cyanobacteria. This study reveals a key step in arsenosugar biosynthesis and also a new paradigm in radical SAM chemistry, highlighting the catalytic diversity of this superfamily of enzymes.

Characterization of NucPNP and NucV involved in the early steps of nucleocidin biosynthesis in Streptomyces calvus.

Nucleocidin 1 produced by Streptomyces calvus is one of five characterized natural products containing fluorine. It was discovered in 1956, but its biosynthesis is not yet completely resolved. Recently, the biosynthetic gene cluster of 1 was identified. The nucPNP gene, which was initially annotated as orf206 and encodes a putative purine nucleoside phosphorylase, is essential for nucleocidin production. In this study, we performed in vitro assays and showed NucPNP produced adenine 3 from methylthioadenosine (MTA) 2 and adenosine 4. We also showed the downstream enzyme, NucV annotated as adenine phosphoribosyltransferase (APRT), catalyzes AMP formation from adenine 3 and 5-phospho-α-d-ribose-1-diphosphate (PRPP) 5. However, the catalytic efficiency of NucV was much slower than its homolog ScAPRT involved in the biosynthesis of canonical purine nucleoside in the same strain. These results provide new insights in nucleocidin biosynthesis and could guide future research on organofluorine formation.

Sulfonium-Based Homolytic Substitution Observed for the Radical SAM Enzyme HemN.

Sulfur-based homolytic substitution (SH reaction) plays an important role in synthetic chemistry, yet whether such a reaction could occur on the positively charged sulfonium compounds remains unknown. In the study of the anaerobic coproporphyrinogen III oxidase HemN, a radical S-adenosyl-l-methionine (SAM) enzyme involved in heme biosynthesis, we observed the production of di-(5'-deoxyadenosyl)methylsulfonium, which supports a deoxyadenosyl (dAdo) radical-mediated SH reaction on the sulfonium center of SAM. The sulfonium-based SH reactions were then investigated in detail by density functional theory calculations and model reactions, which showed that this type of reactions is thermodynamically favorable and kinetically competent. These findings represent the first report of sulfonium-based SH reactions, which could be useful in synthetic chemistry. Our study also demonstrates the remarkable catalytic promiscuity of the radical SAM superfamily enzymes.

Design of two isoreticular Cd-biphenyltetracarboxylate frameworks for dye adsorption, separation and photocatalytic degradation.

Two novel isoreticular cadmium metal-organic frameworks (MOFs) with the framework formula of [Cd2(BPTC)(solvent)3] (H4BPTC = 3,3',5,5'-biphenyltetracarboxylic acid) have been constructed under diverse reaction conditions and characterized by single crystal X-ray diffraction, PXRD, IR and TGA. The neutral 3D frameworks of 1 and 2 with one-dimensional (1D) rhombic channels exhibit both distinct uptake and good selectivity for cationic methylene blue (MB) dye molecules. The adsorption capacity and adsorption kinetic constant of 2 are greater than those of 1, showing the importance of porosity and pore size during the adsorption. Moreover, both MOFs show effective degradation of rhodamine B (RhB) and methyl orange (MO) dyes under UV light irradiation.

Biosynthesis of the nosiheptide indole side ring centers on a cryptic carrier protein NosJ.

Nosiheptide is a prototypal thiopeptide antibiotic, containing an indole side ring in addition to its thiopeptide-characteristic macrocylic scaffold. This indole ring is derived from 3-methyl-2-indolic acid (MIA), a product of the radical S-adenosylmethionine enzyme NosL, but how MIA is incorporated into nosiheptide biosynthesis remains to be investigated. Here we report functional dissection of a series of enzymes involved in nosiheptide biosynthesis. We show NosI activates MIA and transfers it to the phosphopantetheinyl arm of a carrier protein NosJ. NosN then acts on the NosJ-bound MIA and installs a methyl group on the indole C4, and the resulting dimethylindolyl moiety is released from NosJ by a hydrolase-like enzyme NosK. Surface plasmon resonance analysis show that the molecular complex of NosJ with NosN is much more stable than those with other enzymes, revealing an elegant biosynthetic strategy in which the reaction flux is controlled by protein-protein interactions with different binding affinities.Thiopeptides such as nosiheptide are clinically-interesting antimicrobial natural products. Here the authors show the functional dissection of a series of enzymes involved in nosiheptide biosynthesis, revealing a unique biosynthetic pathway that centers on a previously-unknown carrier protein.

A mechanistic study of the non-oxidative decarboxylation catalyzed by the radical S-adenosyl-l-methionine enzyme BlsE involved in blasticidin S biosynthesis.

Decarboxylation is a fundamentally important reaction in biology and involves highly diverse mechanisms. Here we report a mechanistic study of the non-oxidative decarboxylation catalyzed by BlsE, a radical S-adenosyl-l-methionine (SAM) enzyme involved in blasticidin S biosynthesis. Through a series of biochemical analysis with isotopically labeled reagents, we show that the BlsE-catalyzed reaction is initiated by the 5'-deoxyadenosyl (dAdo) radical-mediated hydrogen abstraction from a sugar carbon of the substrate cytosylglucuronic acid (CGA), and does not involve a carboxyl radical as has been proposed for 4-hydroxyphenylacetate decarboxylase (HPAD). Our study reveals that BlsE represents a mechanistically new type of radical-based decarboxylase.

Biosynthetic Insights into Linaridin Natural Products from Genome Mining and Precursor Peptide Mutagenesis.

Linaridin is a small class of peptide natural products belonging to the ribosomally synthesized and post-translationally modified peptides (RiPPs) superfamily. By an extensive genome-wide survey of linaridin biosynthetic genes, we show that this class of natural products is widespread in nature and possesses vast structural diversity. The linaridin precursor peptides are relatively conserved in the N-termini but have diverse sequences in the core region, which appear to have coevolved with the biosynthetic enzymes. Using the prototypic linaridin cypemycin as a model, we have explored the structure-activity relationships involved in precursor peptide maturation and generated a diverse set of novel cypemycin variants, among which the T2S variant exhibits enhanced activity against Micrococcus luteus. Our results reveal valuable insights into linaridin biosynthesis and highlight the potential to explore this class of natural products by genome mining and by biosynthetic engineering studies.

Reactivity of the nitrogen-centered tryptophanyl radical in the catalysis by the radical SAM enzyme NosL.

The radical SAM tryptophan (Trp) lyase NosL involved in nosiheptide biosynthesis catalyzes two parallel reactions, converting l-Trp to 3-methyl-2-indolic acid (MIA) and to dehydroglycine and 3-methylindole, respectively. The two parallel reactions diverge from a nitrogen-centered tryptophanyl radical intermediate. Here we report an investigation on the intrinsic reactivity of the tryptophanyl radical using a chemical model study and DFT calculations. The kinetics of the formation and fragmentation of this nitrogen-centered radical in NosL catalysis were also studied in detail. Our analysis explains the intriguing catalytic promiscuity of NosL and highlights the remarkable role this enzyme plays in achieving an energetically highly unfavorable transformation.

Tuning of valence States, bonding types, hierarchical structures, and physical properties in copper/halide/isonicotinate system.

Seven cupric halide coordination polymers, namely [Cu5(OH)3Br3(ina)4] (1), [Cu5(OH)3Cl3(ina)4] (2), [Cu2(OH)Cl(ina)2] (3), [Cu3(OH)2Cl2(ina)2]·2H2O (4), [Cu3(OH)2Br2(ina)2]·2H2O (5), [Cu2Cl2(ina)2(H2O)2] (6), [Cu2Cl(ina)2(gca)(H2O)] (7), cupric complex templated cuprous halide [Cu(II)(Me-ina)2(H2O)][Cu(I)5Br7] (8), and organic templated cuprous halide Me2-ina[Cu2Br3] (9) (Hina = isonicotinic acid), were prepared from the starting materials of cupric halide and Hina via fine-tuning solvothermal reactions. According to valence states of copper, 1-7 are copper(II) complexes, 8 is a mixed-valent Cu(I,II) complex, while 9 is a Cu(I) compound. According to bonding types of halides, nine complexes can be classified as three types: complexes 1-3 include only normal X-Cu bond (X = halide); complexes 4-7 include normal X-Cu bond and X···Cu weak bond; complexes 8 and 9 include normal X-Cu bond and X···H-C halogen hydrogen bonds. Complexes 1 and 2 are isomorphic three-dimensional (3D) pcu topological metal organic frameworks (MOFs) with butterfly-like Cu4(µ3-OH)2X2 and steplike Cu6(µ3-OH)4 cores as nodes, showing strong ferromagnetic couplings. Complex 3 also is a pcu topological MOF with only butterfly-like Cu4(µ3-OH)2Cl2 clusters as nodes, presenting spin canting antiferromagnetic behavior. Isostructural 4 and 5 are Cu3(OH)2 clusters based two-dimensional (2D) (4,4) layers, which are extended into 3D eight-connected networks via weak Cu···X bonds, showing ferromagnetic coupling. Antiferromagnetic 6 is a simple one-dimensional coordination polymer, which is extended via weak Cu···Cl bonds into 3D (3,4)-connected networks. Paramagnetic 7 is a ladderlike polymer, which is extended into 2D (3,4)-connected layer via weak Cu···Cl bonds. The syntheses of polymeric cupric complexes 1-7 mainly result from differences in reactant ratio and pH value. Utilization of reducing methanol generated novel cubane-containing [Cu5Br7](2-) chain templated by paddlewheel-like [Cu(II)(Me-ina)2](2+) 8 and face-shared dimer-containing [Cu2Br3](-) chain templated by N-methylated and O-esterificated Me2-ina 9. Complex 9 exhibits a strong red emission and a weaker green emission upon excitation.

The first ionothermal synthesis of a 3D ferroelectric metal-organic framework with colossal dielectric constant.

A novel 3D (4,6)-connected topological architecture, obtained under ionothermal conditions by using 1-ethyl-3-methyl imidazolium bromide ([EMI]Br) as solvent and structure-directing agent, presents a non-centrosymmetric polar packing arrangement showing an interesting ferroelectric property.

[Case-control study of risk factors in cholangiocarcinoma].

OBJECTIVE: To investigate the risk factors of intrahepatic cholangiocarcinoma (ICC) and extrahepatic cholangiocarcinoma (ECC). METHODS: The clinicopathological data of 190 patients with cholangiocarcinomas (61 ICC and 129 ECC) diagnosed and treated in the Peking Union Medical College Hospital between 1998 and 2008 were collected. The clinicopathological data of 380 matched healthy controls were also collected. The information about liver diseases, family history, diabetes, smoking and drinking were recorded and analyzed. RESULTS: The positive rate of HBsAg(+) and anti-HBc(+), HBsAg(-) and anti-HBc(+) and the incidence of choledocholithiasis or hepatolithiasis in ICC patients were 27.9%, 50.8% and 14.8%, respectively. The incidence of diabetes mellitus, cholecystolithiasis, choledocholithiasis or hepatolithiasis and previous cholecystectomy in ECC patients were 18.6%, 15.5%, 18.6% and 13.2%, respectively. The incidences of all above mentioned factors in the ICC or ECC patients were significantly higher than that in the controls (P < 0.05). Compared with the patients with ECC, the ICC patients had a significantly higher cirrhosis rate (P < 0.05). CONCLUSION: Our study results show that choledocholithiasis or hepatolithiasis, liver cirrhosis and chronic HBV infection are possible risk factors for intrahepatic cholangiocarcinoma, while choledocholithiasis or hepatolithiasis, diabetes mellitus, cholecystolithiasis, history of cholecystectomy are risk factors for extrahepatic cholangiocarcinoma.

[Expression of hepatocyte-enriched transcriptional factors during the differentiation of bone marrow mesenchymal stem cell-derived hepatocytes].

OBJECTIVE: To study the expression and distribution of hepatocyte-enriched transcriptional factors during the differentiation of hepatocyte by rat bone marrow stem cells in vitro. METHODS: Mesenchymal stem cells were isolated from rat bone marrow and induced into mature hepatocyte in vitro. The mRNA expression levels of hepatocyte nuclear factor 4 alpha (HNF4 alpha), CCAAT enhancer binding protein (C/EBP) alpha and beta were compared between induced and non-induced cultures using semi-quantitative reverse transcription-polymerase chain reaction. The distribution pattern of HNF4 alpha was detected by immunofluorescence staining and observed by fluorescence microscope. RESULTS: Transcriptional factors HNF4 alpha, C/EBP alpha, and C/EBP beta were expressed in the induced cells during the culture process. The mRNA expression levels of HNF4 alpha and C/EBP alpha were significantly higher in induced cultures than those in non-induced cultures in the early stage, whereas C/EBP beta expression was significantly up-regulated in induced cultures at the late stage (P < 0.05). Immunofluorescence staining showed that HNF4 alpha was located in the cell nucleus of differentiated cells. CONCLUSION: The characteristic time-dependent expression of transcriptional factors HNF4 alpha, C/EBP alpha, and C/EBP beta during the hepatocyte differentiation by bone marrow stem cells demonstrates that the expressions of these transcriptional factors are closely related to the initiation and maintenance of hepatocyte differentiation.

[Ursodeoxycholic acid inhibits hepatocyte-like cell apoptosis by down-regulating the expressions of Bax and Caspase-3].

OBJECTIVE: To investigate the mechanism of ursodeoxycholic acid (UDCA) in hepatocyte apoptosis using differentiated hepatocytes derived from bone marrow mesenchymal cells. METHODS: Rat bone marrow mesenchymal cell was induced into mature hepatocytes in vitro and then treated with PBS (Cont), deoxycholic acid (DCA), DCA plus UDCA (U + D) or UDCA alone (UDCA). Cell apoptosis was detected by Hoechst staining and Caspase-3 activity measurement. The mRNA expressions of p53 and Bax were measured by semi-quantitative RT-PCR and real-time RT-PCR. The Bax protein expression was detected by immunohistochemistry. RESULTS: In comparison with Cont, DCA obviously induced hepatocyte apoptosis as measured by an increased cell count and a higher Caspase-3 activity (P < 0.05). These increments could be inhibited by addition of UDCA. The expressions of p53 and Bax in hepatocytes were up-regulated by DCA. These up-expressions could also be inhibited by UDCA. The DCA-induced increased count of Bax-positive cells could be reduced by UDCA. CONCLUSION: UDCA inhibits DCA-induced hepatocyte apoptosis by down-regulating the expression of p53/Bax signal molecule.