Both middle and large envelope proteins can mediate neutralization of hepatitis B virus infectivity by anti-preS2 antibodies: escape by naturally occurring preS2 deletions.

Hepatitis B virus (HBV) expresses co-terminal large (L), middle (M), and small (S) envelope proteins containing preS1/preS2/S, preS2/S, and S domain alone, respectively. S and preS1 domains mediate sequential virion attachment to heparan sulfate proteoglycans and sodium taurocholate cotransporting polypeptide (NTCP), respectively, which can be blocked by anti-S and anti-preS1 antibodies. How anti-preS2 antibodies neutralize HBV infectivity remains enigmatic. The late stage of chronic HBV infection often selects for mutated preS2 translation initiation codon to prevent M protein expression, or in-frame preS2 deletions to shorten both L and M proteins. When introduced to infectious clone of genotype C or D, both M-minus mutations and most 5' preS2 deletions sustained virion production. Such mutant progeny viral particles were infectious in NTCP-reconstituted HepG2 cells. Neutralization experiments were performed on the genotype D clone. Although remaining susceptible to anti-preS1 and anti-S neutralizing antibodies, M-minus mutants were only partially neutralized by two anti-preS2 antibodies tested while preS2 deletion mutants were resistant. By infection experiments using viral particles with lost versus increased M protein expression, or a neutralization escaping preS2 deletion only present on L or M protein, we found that both full-length L and M proteins contributed to virus neutralization by the two anti-preS2 antibodies. Thus, immune escape could be a driving force for the selection of M-minus mutations, and especially preS2 deletions. The fact that both L and M proteins could mediate neutralization by anti-preS2 antibodies may shed light on the underlying molecular mechanism.IMPORTANCEThe large (L), middle (M), and small (S) envelope proteins of hepatitis B virus (HBV) contain preS1/preS2/S, preS2/S, and S domain alone, respectively. The discovery of heparan sulfate proteoglycans and sodium taurocholate cotransporting polypeptide (NTCP) as the low- and high-affinity HBV receptors could explain neutralizing potential of anti-S and anti-preS1 antibodies, respectively, but how anti-preS2 neutralizing antibodies work remains enigmatic. In this study, we found two M-minus mutants in the context of genotype D partially escaped two anti-preS2 neutralizing antibodies in NTCP-reconstituted HepG2 cells, while several naturally occurring preS2 deletion mutants escaped both antibodies. By point mutations to eliminate or enhance M protein expression, and by introducing preS2 deletion selectively to L or M protein, we found binding of anti-preS2 antibodies to both L and M proteins contributed to neutralization of wild-type HBV infectivity. Our finding may shed light on the possible mechanism(s) whereby anti-preS2 antibodies neutralize HBV infectivity.

Improved Cardiac Performance and Decreased Arrhythmia in Hypertrophic Cardiomyopathy With Non-ß-Blocking R-Enantiomer Carvedilol.

BACKGROUND: Hypercontractility and arrhythmia are key pathophysiologic features of hypertrophic cardiomyopathy (HCM), the most common inherited heart disease. ß-Adrenergic receptor antagonists (ß-blockers) are the first-line therapy for HCM. However, ß-blockers commonly selected for this disease are often poorly tolerated in patients, where heart-rate reduction and noncardiac effects can lead to reduced cardiac output and fatigue. Mavacamten, myosin ATPase inhibitor recently approved by the US Food and Drug Administration, has demonstrated the ability to ameliorate hypercontractility without lowering heart rate, but its benefits are so far limited to patients with left ventricular (LV) outflow tract obstruction, and its effect on arrhythmia is unknown. METHODS: We screened 21 ß-blockers for their impact on myocyte contractility and evaluated the antiarrhythmic properties of the most promising drug in a ventricular myocyte arrhythmia model. We then examined its in vivo effect on LV function by hemodynamic pressure-volume loop analysis. The efficacy of the drug was tested in vitro and in vivo compared with current therapeutic options (metoprolol, verapamil, and mavacamten) for HCM in an established mouse model of HCM (Myh6R403Q/+ and induced pluripotent stem cell (iPSC)-derived cardiomyocytes from patients with HCM (MYH7R403Q/+). RESULTS: We identified that carvedilol, a ß-blocker not commonly used in HCM, suppresses contractile function and arrhythmia by inhibiting RyR2 (ryanodine receptor type 2). Unlike metoprolol (a ß1-blocker), carvedilol markedly reduced LV contractility through RyR2 inhibition, while maintaining stroke volume through α1-adrenergic receptor inhibition in vivo. Clinically available carvedilol is a racemic mixture, and the R-enantiomer, devoid of ß-blocking effect, retains the ability to inhibit both α1-receptor and RyR2, thereby suppressing contractile function and arrhythmias without lowering heart rate and cardiac output. In Myh6R403Q/+ mice, R-carvedilol normalized hyperdynamic contraction, suppressed arrhythmia, and increased cardiac output better than metoprolol, verapamil, and mavacamten. The ability of R-carvedilol to suppress contractile function was well retained in MYH7R403Q/+ iPSC-derived cardiomyocytes. CONCLUSIONS: R-enantiomer carvedilol attenuates hyperdynamic contraction, suppresses arrhythmia, and at the same time, improves cardiac output without lowering heart rate by dual blockade of α1-adrenergic receptor and RyR2 in mouse and human models of HCM. This combination of therapeutic effects is unique among current therapeutic options for HCM and may particularly benefit patients without LV outflow tract obstruction.

The Association Between Thymidylate Synthase Gene Polymorphisms and the Risk of Ischemic Stroke in Chinese Han Population.

Family history of hypertension, smoking, diabetes and alcohol consumption and atherosclerotic plaque were identified as common risk factors in IS. We aimed at investigating the relationship between Thymidylate Synthase (TS) gene polymorphisms and ischemic stroke (IS).This case-control research selected and genotyped three single nucleotide polymorphisms (SNPs)of TS( rs699517, rs2790, and rs151264360) with Sanger sequencing in Chinese Han population. We also adopted logistic regression analysis in genetic models for calculating odds ratios and 95% confidence intervals. Genotype-Tissue Expression(GTEx) database analyzed the tissue-specific expression and TS polymorphisms. The ischemic stroke patients showed higher low-density lipoprotein cholesterol and total homocysteine (tHcy). It was found that patients with the TT genotype of rs699517 and GG genotype of rs2790 had larger degrees of tHcy than those with CC + CT genotypes and AA + AG genotypes, respectively. The genotype distribution of the three SNPs did not deviate from Hardy-Weinberg equilibrium (HWE). Haplotype analysis showed that T-G-del was the major haplotype in IS, and C-A-ins was the major haplotype in controls. GTEx database indicated that the rs699517 and rs2790 increased the expression of TS in healthy human and associated with TS expression level in a single tissue. In conclusion: This study has shown that TS rs699517 and rs2790 were significantly related to ischemic stroke patients.

Prenylated C6-C3 derivatives from the root of Illicium ternstroemioides with antiviral activity.

Six previously undescribed prenylated C6-C3 derivatives (1-6) were isolated from the root of Illicium ternstroemioides A. C. Smith. Their structures were elucidated based on extensive spectroscopic analyses (UV, IR, 1D and 2D NMR, and HRESIMS). The absolute configurations of 1-3 were determined using electronic circular dichroism (ECD), and Mo2(OAc)4 induced circular dichroism (ICD). Compound 3 exhibited weak activity against Coxsackievirus B3 with an IC50 value of 33.3 µM, and compound 5 exhibited more potent activity against Coxsackievirus B3 with an IC50 value of 6.4 µM.

Bioactive prenylated c6-c3 derivatives from the roots of Illicium brevistylum.

Three new prenylated C6-C3 compounds (1-3), together with two known prenylated C6-C3 compounds (4-5) and one known C6-C3 derivative (6), were isolated from the roots of Illicium brevistylum A. C. Smith. The structures of 1-3 were elucidated by spectroscopic methods including 1D and 2D NMR, HRESIMS, CD experiments and ECD calculations. The structure of illibrefunone A (1) was confirmed by single-crystal X-ray diffraction analysis. All compounds were evaluated in terms of their anti-inflammatory potential on nitric oxide (NO) generation in lipopolysaccharide-stimulated murine RAW264.7 macrophages and murine BV2 microglial cells, antiviral activity against Coxsackievirus B3 (CVB3) and influenza virus A/Hanfang/359/95 (H3N2). Compounds 3 and 4 exhibited potent inhibitory effects on the production of NO in RAW 264.7 cells with IC50 values of 20.57 and 12.87 µM respectively, which were greater than those of dexamethasone (positive control). Compounds 1 and 4-6 exhibited weak activity against Coxsackievirus B3, with IC50 values ranging from 25.87 to 33.33 µM.

Cadinane sesquiterpenes from the stems and branches of Illicium ternstroemioides.

Three new cadinane sesquiterpenes (1-3) and three known sesquiterpenes were isolated from the stems and branches of Illicium ternstroemioides A. C. Smith. The structures of the new compounds were elucidated by extensive analysis of spectroscopic and HRESIMS data. The structures of illiternins A-C (1-3) were confirmed by single crystal X-ray diffraction, allowing for the determination of their absolute configurations. Compounds 3 and 6 exhibited antiviral activity against Coxsackievirus B3 with IC50 values of 33.3 and 57.7 µM, respectively.

Study of Bitespiramycin Distribution in Rats and Cerebrospinal Fluid of Patients by a Sensitive LC-MS/MS Method with Rapid Sample Preparation.

Bitespiramycin, has been shown to have a therapeutic effect against respiratory tract inflammation, including a potential effect against COVID-19. A current clinical trial in China showed that bitespiramycin was an effective treatment for severe pneumonia and intracranial infection. However, there is lack of an analytical method to elucidate the distribution of bitespiramycin. In this study, a highly sensitive, rapid and reliable UPLC-MS/MS method was developed to comprehensively characterize the bitespiramycin distribution in various bio-samples, which is significantly improved upon the published work. A rapid sample preparation method was developed by using n-butanol as the solvent to extract bitespiramycin from different bio-samples. The extract was then directly analyzed by UPLC-MS/MS coupled with an alkaline-resistant column after centrifugation which avoids the time-consuming concentration process under nitrogen and redissolution. The method was employed to accurately quantify bitespiramycin and its metabolites in rat plasma, tissues, and human cerebrospinal fluid. Notably, the presence of bitespiramycin and its metabolites was identified for the first time in various rat organs including brain, testis, bladder and prostate as well as in human cerebrospinal fluid. This newly developed approach shows great promise for drug distribution assays including other antibiotics and can help elucidate the ADME of bitespiramycin.

The formation of a lithium-iridium complex hydride toward ammonia synthesis.

Noble metal elements are focal catalytic candidates for many chemical processes, but have received little attention in the field of nitrogen fixation except ruthenium and osmium. Iridium (Ir), as a representative, has been shown to be catalytically inactive for ammonia synthesis because of its weak nitrogen adsorption and severe competitive adsorption of H over N that strongly inhibits the activation of N2 molecules. Here we show that, upon compositing with lithium hydride (LiH), iridium can catalyze ammonia formation at much enhanced reaction rates. The catalytic performance of the LiH-Ir composite can be further improved by dispersion on a MgO support with a high specific surface area. At 400 °C and 10 bar, the MgO-supported LiH-Ir (LiH-Ir/MgO) catalyst shows a ca. 100-fold increase in activity compared to the bulk LiH-Ir composite and the MgO-supported Ir metal catalyst (Ir/MgO). The formation of a lithium-iridium complex hydride phase was identified and characterized, and this phase may be responsible for the activation and hydrogenation of N2 to NH3.

Barium hydride activates Ni for ammonia synthesis catalysis.

Nickel (Ni) metal has long been considered to be far less active for catalytic ammonia synthesis as compared to iron, cobalt, and ruthenium. Herein, we show that Ni metal synergized with barium hydride (BaH2) can catalyse ammonia synthesis with an activity comparable to that of an active Cs-Ru/MgO catalyst typically below 300 °C. Kinetic analyses show that the addition of BaH2 makes the apparent activation energy for the Ni catalyst decrease dramatically from 150 kJ mol-1 to 87 kJ mol-1. This result together with N2-TPR experiments suggests a strong synergistic effect between Ni and BaH2 for promoting N2 activation and hydrogenation to NH3. It is suggested that an intermediate [N-H] species is generated upon N2 fixation and then is hydrogenated to NH3 with the regeneration of hydride species, forming a catalytic cycle.

Graphene/C2N lateral heterostructures as promising anode materials for lithium-ion batteries.

Two-dimensional (2D) heterostructures have been proposed as potential anode materials for lithium-ion batteries due to their large surface areas and excellent electronic properties. In this study, we employ first-principles calculations to investigate the structural stability, electronic properties, and ion diffusion behaviors of 2D graphene/C2N lateral heterostructures. Three species of (5, 26), (11, 26), and (17, 26) heterostructures are chosen to explore the effects of graphene components on electronic properties. The results show that graphene/C2N lateral heterostructures exhibit good dynamic stability due to a small lattice mismatch and strong chemical interaction at the heterojunction interface. By introducing zero-gap graphene, these heterostructures acquire good electronic conductivity with small direct band gaps. The component ratio of graphene can significantly tune the band gap, showing a monotonic decrease as the ratio increases. Moreover, the introduction of C2N components can greatly improve the lithium capacities of heterostructures. Small diffusion energy barriers (0.257-0.273 eV) and a low average operating voltage of 0.758 V are observed in graphene/C2N heterostructures. The effects of graphene components and valence states on Li migration are discussed. Our results demonstrate that the graphene/C2N lateral heterostructure can effectively combine the advantages of graphene and the C2N monolayer, showing great promise as an anode material for lithium-ion batteries.

The structure of analogical reasoning in bioethics.

Casuistry, which involves analogical reasoning, is a popular methodological approach in bioethics. The method has its advantages and challenges, which are widely acknowledged. Meta-philosophical reflection on exactly how bioethical casuistry works and how the challenges can be addressed is limited. In this paper we propose a framework for structuring casuistry and analogical reasoning in bioethics. The framework is developed by incorporating theories and insights from the philosophy of science: Mary Hesse's ideas on horizontal and vertical relations in analogical reasoning in the sciences, Paul Bartha's articulation model of analogical reasoning and Daniel Steel's insights on mechanism-based extrapolation in biomedical research. Adopting our framework results in two practical benefits: it sets methodological standards for analogical reasoning and enables us to compare and evaluate diverging lines of analogical reasoning in a systematic way. Adopting the framework also has theoretical benefits: it helps to understand how analogical reasoning can have moral normativity; it pinpoints exactly where moral principles or theories enter analogical reasoning; and it helps to understand why casuistry is an attractive method in bioethics and in applied ethics more generally.

From Dinitrogen to N-Containing Organic Compounds: Using Li2 CN2 as a Synthon.

Through the synergies of a heterogeneous synthetic approach and a homogeneous synthetic methodology, N-containing organic compounds can be synthesized via activated N-containing species prepared from N2 gas and suitable carbon sources. From N2 , carbon, and LiH, we have previously succeeded in the high-yield preparation of Li2 CN2 as the activated N-containing species. In this work, we applied Li2 CN2 as a novel synthetic synthon for constructing N-containing organic compounds. A series of reaction models, including a substitution reaction, cycloaddition reaction, and transition metal-catalyzed coupling reaction, were successfully performed using Li2 CN2 under mild conditions. Various valuable cyanamides, carbodiimides, N-aryl cyanamides and 1,2,4-triazole derivatives were readily synthesized in moderate to excellent yields. With this method, the 15 N-labeled products, including oxazolidine derivatives with anti-cancer activity, could also be facilely prepared from 15 N2 gas.

Lost Small Envelope Protein Expression from Naturally Occurring PreS1 Deletion Mutants of Hepatitis B Virus Is Often Accompanied by Increased HBx and Core Protein Expression as Well as Genome Replication.

Hepatitis B virus (HBV) transcribes coterminal mRNAs of 0.7 to 3.5 kb from the 3.2-kb covalently closed circular DNA, with the 2.1-kb RNA being most abundant. The 0.7-kb RNA produces HBx protein, a transcriptional transactivator, while the 3.5-kb pregenomic RNA (pgRNA) drives core and P protein translation as well as genome replication. The large (L) and small (S) envelope proteins are translated from the 2.4-kb and 2.1-kb RNAs, respectively, with the majority of the S protein being secreted as noninfectious subviral particles and detected as hepatitis B surface antigen (HBsAg). pgRNA transcription could inhibit transcription of subgenomic RNAs. The present study characterized naturally occurring in-frame deletions in the 3' preS1 region, which not only codes for L protein but also serves as the promoter for 2.1-kb RNA. The human hepatoma cell line Huh7 was transiently transfected with subgenomic expression constructs for envelope (and HBx) proteins, dimeric constructs, or constructs mimicking covalently closed circular DNA. The results confirmed lost 2.1-kb RNA transcription and HBsAg production from many deletion mutants, accompanied by increases in other (especially 2.4-kb) RNAs, intracellular HBx and core proteins, and replicative DNA but impaired virion and L protein secretion. The highest intracellular L protein levels were achieved by mutants that had residual S protein expression or retained the matrix domain in L protein. Site-directed mutagenesis of a high replicating deletion mutant suggested that increased HBx protein expression and blocked virion secretion both contributed to the high replication phenotype. Our findings could help explain why such deletions are selected at a late stage of chronic HBV infection and how they contribute to viral pathogenesis. IMPORTANCE Expression of hepatitis B e antigen (HBeAg) and overproduction of HBsAg by wild-type HBV are implicated in the induction of immune tolerance to achieve chronic infection. How HBV survives the subsequent immune clearance phase remains incompletely understood. Our previous characterization of core promoter mutations to reduce HBeAg production revealed the ability of the 3.5-kb pgRNA to diminish transcription of coterminal RNAs of 2.4 kb, 2.1 kb, and 0.7 kb. The later stage of chronic HBV infection often selects for in-frame deletions in the preS region. Here, we found that many 3' preS1 deletions prevented transcription of the 2.1-kb RNA for HBsAg production, which was often accompanied by increases in intracellular 3.5-, 0.7-, and especially 2.4-kb RNAs, HBx and core proteins, and replicative DNA but lost virion secretion. These findings established the biological consequences of preS1 deletions, thus shedding light on why they are selected and how they contribute to hepatocarcinogenesis.

Fine Mapping and Candidate Gene Prediction of Tuber Shape Controlling Ro Locus Based on Integrating Genetic and Transcriptomic Analyses in Potato.

Tuber shape is one of the most important quality traits in potato appearance. Since poor or irregular shape results in higher costs for processing and influences the consumers' willingness to purchase, breeding for shape uniformity and shallow eye depth is highly important. Previous studies showed that the major round tuber shape controlling locus, the Ro locus, is located on chromosome 10. However, fine mapping and cloning of tuber shape genes have not been reported. In this study, the analyses of tissue sectioning and transcriptome sequencing showed that the developmental differences between round and elongated tuber shapes begin as early as the hook stage of the stolon. To fine map tuber shape genes, a high-density genetic linkage map of the Ro region on chromosome 10 based on a diploid segregating population was constructed. The total length of the genetic linkage map was 25.8 cM and the average marker interval was 1.98 cM. Combined with phenotypic data collected from 2014 to 2017, one major quantitative trait locus (QTL) for tuber shape was identified, which explained 61.7-72.9% of the tuber shape variation. Through the results of genotyping and phenotypic investigation of recombinant individuals, Ro was fine mapped in a 193.43 kb interval, which contained 18 genes. Five candidate genes were preliminarily predicted based on tissue sections and transcriptome sequencing. This study provides an important basis for cloning Ro gene(s).

Transition-Metal-Free Barium Hydride Mediates Dinitrogen Fixation and Ammonia Synthesis.

Transition-metal-mediated dinitrogen fixation has been intensively investigated. The employment of main group elements for this vital reaction has recently sparked interest because of new dinitrogen reaction chemistry. We report ammonia synthesis via a chemical looping process mediated by a transition-metal-free barium hydride (BaH2 ). Experimental and computational studies reveal that the introduction of hydrogen vacancies is essential for creating multiple coordinatively unsaturated Ba sites for N2 activation. The adjacent lattice hydridic hydrogen (H- ) then undergoes both reductive elimination and reductive protonation to convert N2 to NHx . The ammonia production rate supports this hydride-vacancy mechanism via a chemical looping route that far exceeds that of a catalytic process. The BaH2 -mediated chemical looping process has prospects in future technologies for ammonia synthesis using transition-metal-free materials.

Naturally occurring 5' preS1 deletions markedly enhance replication and infectivity of HBV genotype B and genotype C.

BACKGROUND AND AIMS: Deletion of 15-nucleotide or 18-nucleotide (nt) covering preS1 ATG frequently arises during chronic infection with HBV genotypes B and C. Since the second ATG is 33nt downstream, they truncate large (L) envelope protein by 11 residues like wild-type genotype D. This study characterised their functional consequences. METHODS: HBV genomes with or without deletion were amplified from a patient with advanced liver fibrosis and assembled into replication competent 1.1mer construct. Deletion, insertion or point mutation was introduced to additional clones of different genotypes. Viral particles concentrated from transfected HepG2 cells were inoculated to sodium taurocholate cotransporting polypeptide (NTCP)-reconstituted HepG2 (HepG2/NTCP) cells or differentiated HepaRG cells, and HBV RNA, DNA, proteins were monitored. RESULTS: From transfected HepG2 cells, the 15-nt and 18-nt deletions increased HBV RNA, replicative DNA and extracellular virions. When same number of viral particles was inoculated to HepG2/NTCP cells, the deletion mutants showed higher infectivity. Conversely, HBV infectivity was diminished by putting back the 18nt into naturally occurring genotype C deletion mutants and by adding 33nt to genotype D. Infectivity of full-length genotype C clones was also enhanced by mutating the first ATG codon of the preS1 region but diminished by mutating the second in-frame ATG. Removing N-terminal 11 residues from preS1 peptide 2-59 of genotype C potentiated inhibition of HBV infection and enhanced binding to HepG2/NTCP cells. CONCLUSIONS: The 15-nt and 18-nt deletions somehow increase HBV RNA, replicative DNA and virion production. Shortened L protein is more efficient at mediating HBV infection.

Thermodynamic Properties of Ammonia Production from Hydrogenation of Alkali and Alkaline Earth Metal Amides.

Thermodynamic properties of alkali and alkaline earth metal amides are critical for their performance in hydrogen storage as well as catalytic ammonia synthesis. In this work, the ammonia equilibrium concentrations of LiNH2 , KNH2 and Ba(NH2 )2 at ca.10 bar of hydrogen pressure and different temperatures were measured by using a high-pressure gas-solid reaction system equipped with a conductivity meter. Hydrogenation of KNH2 gives the highest ammonia equilibrium concentration, followed by Ba(NH2 )2 and LiNH2 . Based on these data, the entropy and enthalpy changes of the reaction of ANH2 +H2 →AH+NH3 (A=Li, K, and Ba) were obtained from the van't Hoff equation. These thermodynamic parameters provide important information on the understanding of metal amides in catalytic ammonia synthesis reaction.

Transcriptome Profiling Reveals Effects of Drought Stress on Gene Expression in Diploid Potato Genotype P3-198.

Potato (Solanum tuberosum L.) is one of the three most important food crops worldwide; however, it is strongly affected by drought stress. The precise molecular mechanisms of drought stress response in potato are not very well understood. The diploid potato genotype P3-198 has been verified to be highly resistant to drought stress. Here, a time-course experiment was performed to identify drought resistance response genes in P3-198 under polyethylene glycol (PEG)-induced stress using RNA-sequencing. A total of 1665 differentially expressed genes (DEGs) were specifically identified, and based on gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the transcription factor activity, protein kinase activity, and the plant hormone signal transduction process were significantly enriched. Annotation revealed that these DEGs mainly encode transcription factors, protein kinases, and proteins related to redox regulation, carbohydrate metabolism, and osmotic adjustment. In particular, genes encoding abscisic acid (ABA)-dependent signaling molecules were significantly differentially expressed, which revealed the important roles of the ABA-dependent signaling pathway in the early response of P3-198 to drought stress. Quantitative real-time PCR experimental verification confirmed the differential expression of genes in the drought resistance signaling pathway. Our results provide valuable information for understanding potato drought-resistance mechanisms, and also enrich the gene resources available for drought-resistant potato breeding.