Novel Pseudo-Two-Dimensional 19F NMR Spectroscopy for Rapid Simultaneous Detection of Amines in Complex Mixture.

Rapid detection of amines in complex mixtures presents a significant challenge. Here, we introduce a novel nuclear magnetic resonance (NMR) method for amine detection utilizing a probe with two fluorine atoms in distinct chemical environments. Upon interaction with an amine, the probe generates two atomic resonance peaks, which are used to create coordinates, revealing fluorine chemical shifts on the 19F NMR spectroscopy. This innovative approach allows for the clear distinction of amine signals in a two-dimensional plane. This method has been effectively employed in analyzing amines in pharmaceuticals and amino acids in Ophiopogon japonicus and dry white wine, providing a robust and general approach for amine analysis.

Translation, cultural adaptation, and validation of the Chinese standardized outcomes in nephrology-hemodialysis fatigue (C-SONG-HD fatigue) scale: a study of Chinese patients undergoing hemodialysis.

OBJECTIVE: This study aimed to translate and culturally adapt the standardized outcomes in nephrology-hemodialysis fatigue (SONG-HD fatigue) scale and to assess the psychometric properties of the Chinese version of the SONG-HD fatigue (C-SONG-HD fatigue) scale. METHODS: Forward and back translations were used to translate the SONG-HD fatigue scale into Chinese. We used the C-SONG-HD fatigue scale to survey Chinese patients undergoing hemodialysis (HD) in China. We examined the distribution of responses and floor and ceiling effects. Cronbach's alpha and McDonald's omega coefficient, intraclass coefficients, and Spearman correlations were used to assess internal consistency reliability, test-retest reliability, and convergent validity, respectively. Responsiveness was also evaluated. RESULTS: In total, 489 participants across southeast China, northwest China, and central China completed the study. The C-SONG-HD fatigue scale had good internal consistency (Cronbach's alpha coefficient 0.861, omega coefficient 0.916), test-retest reliability (intraclass correlation coefficient 0.695), and convergent validity (Spearman correlation 0.691). The analysis of all first-time HD patients did not show notable responsiveness, and only patients with temporary vascular access had good responsiveness with an effect size (ES) of 0.54, a standardized response mean (SRM) of 0.85, and a standard error of measurement (SEM) of 0.77. CONCLUSION: The Chinese version of the SONG-HD fatigue scale showed satisfactory reliability and validity in patients undergoing hemodialysis (HD) in China. It could be used as a tool to measure the fatigue of Chinese HD patients.

Pathogenic and Comparative Genomic Analysis of Ralstonia pseudosolanacearum Isolated from Casuarina.

Casuarina equisetifolia is crucial in protecting coastal regions of China against typhoon attacks but has faced a substantial challenge due to wilt disease caused by pathogens of the Ralstonia solanacearum species complex (RSSC). Although the initial outbreak of Casuarina wilt in the 1970s was effectively controlled by disease-resistant C. equisetifolia varieties, the disease has recently re-emerged in coastal regions of Guangdong. In this study, we report the isolation, characterization, and comparative genomic analysis of 11 RSSC strains from diseased C. equisetifolia at various locations along the coast of Guangdong. Phylogenomic analysis showed that the strains were closely related and clustered with phylotype I strains previously isolated from peanuts. Single-gene-based analysis further suggested these strains could be derived from strains present in Guangdong since the 1980s, indicating a historical context to their current pathogenicity. Casuarina-isolated strains exhibited notably higher virulence against C. equisetifolia and peanuts than the representative RSSC strains GMI1000 and EP1, suggesting host-specific adaptations that possibly contributed to the recent outbreak. Comparative genomic analysis among RSSC strains revealed a largely conserved genome structure and high levels of conservation in gene clusters encoding extracellular polysaccharide biosynthesis, secretion systems, and quorum sensing regulatory systems. However, we also found a number of unique genes in the Casuarina-isolated strains that were absent in GMI1000 and EP1, and vice versa, pointing to potential genetic factors underpinning their differential virulence. These unique genes offer promising targets for future functional studies. Overall, our findings provide crucial insights into the RSSC pathogens causing Casuarina wilt in Guangdong, guiding future efforts in disease control and prevention.

Solvent Effects Used for Optimal Simultaneous Analysis of Amino Acids via 19F NMR Spectroscopy.

19F NMR has been extensively used in simultaneous analysis of multicomponent due to its 100% natural isotope abundance, high NMR-sensitivity, and wide-range chemical shifts. The solvent effects are usually observed in NMR spectroscopy and cause large changes in 19F chemical shifts. Herein, we propose that the simultaneous analysis of a complex mixture can be achieved using solvent effects via 19F NMR spectroscopy, such as a mixture solution of amino acids (AAs). AAs are not only cell-signaling molecules, but are also considered as biomarkers of some diseases. Hence, the analysis of AAs is important for human health and the diagnosis of diseases. In this work, the key to the success of sensing 19 biogenic AAs is the use of 2-fluorobenzaldehyde (2FBA) as a highly sensitive derivatizing agent and solvent effects to produce distinguishable 19F NMR signals. As a result, the resolution of 19F NMR spectroscopy of multiple 2FBA-labeled AAs is obviously higher than other methods based on 19F NMR. Moreover, 14 and 18 AAs can be satisfactorily differentiated and unambiguously identified in different complicated media supporting the growth of mammalian cells. Furthermore, quantification of the concentration of AAs can be made, and the limit of detection reaches 10 µM. Our work provides new insights into the simultaneous analysis of a multicomponent mixture based on solvent effects by 19F NMR spectroscopy.

19F NMR enantiodiscrimination and diastereomeric purity determination of amino acids, dipeptides, and amines.

Chiral amino-group compounds are of significance for human health, such as biogenic amino acids (AAs), dipeptides, and even various drugs. Enantiospecific discrimination of these chiral compounds is vital in diagnosing diseases, identifying pathological biomarkers and enhancing pharmaceutical chemistry research. Here, we report a simple and rapid 19F NMR-based strategy to differentiate chiral AAs, dipeptides, and amines, that were derivatized with (R)-2-(2-fluorophenyl)-2-hydroxyacetic acid ((R)-2FHA). As a result, 19 proteinogenic AAs (37 isomers) as well as Gly could be concurrently resolved. Moreover, various mirror-image dipeptides, such as Ser-His, Leu-Leu, and Ala-Ala, were commendably recognized. Intriguingly, we found that the absolute configuration of AAs in the N-terminus of dipeptides decided the relative 19F chemical shifts between two enantiomers. Besides, the ability of this method for enantiodiscrimination was further demonstrated by non-AA amines, including aromatic and aliphatic amines, and even amines having chiral centers several carbons away from the amino-group. The structurally similar antibiotics, amoxicillin and ampicillin, were well discriminated. Furthermore, this method accurately determines the de or dr values of non-racemic mixtures. Therefore, our strategy provides an effective approach for 19F NMR-based enantiodiscrimination and diastereomeric purity determination of amino-group compounds.

Association of estimated glomerular filtration rate and all-cause mortality in acute pancreatitis: a retrospective analysis.

BACKGROUND: Our primary objective was to explore the association between estimated glomerular filtration rate (eGFR) and all-cause mortality in acute pancreatitis (AP) admission to intensive care units. METHODS: This study is a retrospective cohort analysis based on the Medical Information Mart for Intensive Care III database. The eGFR was calculated based on Chronic Kidney Disease Epidemiology Collaboration equation. Cox models with restricted cubic spline functions were used to evaluated the association of eGFR with all-cause mortality. RESULTS: The mean eGFR was 65.93 ± 38.56 ml/min/1.73 m2 in 493 eligible patients. 28-day mortality was 11.97% (59/ 493), which decreased by 15% with every 10 ml/min/1.73 m2 increase in eGFR. The adjusted hazard ratio (95% confidence interval) was 0.85 (0.76-0.96). A non-linear association was proved between eGFR and all-cause mortality. When eGFR < 57 ml/min/1.73 m2, there was a negative correlation between eGFR and 28-day mortality, hazard ratio (95% CI) was 0.97 (0.95, 0.99). The eGFR was also negatively correlated with in-hospital and in-ICU mortality. Subgroup analysis confirmed that the association between eGFR and 28-day mortality in different characteristics was stable. CONCLUSIONS: The eGFR was negatively correlated with all-cause mortality in AP when eGFR is less than the threshold inflection point.

trans-4-Fluoro-l-proline: A Sensitive 19F NMR Probe for the Rapid Simultaneous Enantiomeric Analysis of Multicomponent Amines.

Simultaneous enantiomeric analysis is especially important for medicine, food security, and life science. Chiral analysis of multicomponent amine mixtures still faces many challenges. Here, our work demonstrates for the first time that a novel chiral derivatizing agent CDApro based on trans-4-fluoro-l-proline (trans4Fpro) has been successfully used for the rapid simultaneous analysis of 22 chiral nonamino acid (non-AA) amines, multicomponent l/d-AAs, or mirror-image dipeptides in a mixture, as well as amines with chiral centers several carbons remote to the amino group. Furthermore, determination of enantiomeric purity and quantification of chiral amines can be made using CDApro, which serves as a robust and powerful reagent for the differentiation of multicomponent chiral amines.

A single subcutaneous or intranasal immunization with adenovirus-based SARS-CoV-2 vaccine induces robust humoral and cellular immune responses in mice.

Optimal vaccines are needed for sustained suppression of SARS-CoV-2 and other novel coronaviruses. Here, we developed a recombinant type 5 adenovirus vector encoding the gene for the SARS-CoV-2 S1 subunit antigen (Ad5.SARS-CoV-2-S1) for COVID-19 immunization and evaluated its immunogenicity in mice. A single immunization with Ad5.SARS-CoV-2-S1 via S.C. injection or I.N delivery induced robust antibody and cellular immune responses. Vaccination elicited significant S1-specific IgG, IgG1, and IgG2a endpoint titers as early as 2 weeks, and the induced antibodies were long lasting. I.N. and S.C. administration of Ad5.SARS-CoV-2-S1 produced S1-specific GC B cells in cervical and axillary LNs, respectively. Moreover, I.N. and S.C. immunization evoked significantly greater antigen-specific T-cell responses compared to unimmunized control groups with indications that S.C. injection was more effective than I.N. delivery in eliciting cellular immune responses. Mice vaccinated by either route demonstrated significantly increased virus-specific neutralization antibodies on weeks 8 and 12 compared to control groups, as well as BM antibody forming cells (AFC), indicative of long-term immunity. Thus, this Ad5-vectored SARS-CoV-2 vaccine candidate showed promising immunogenicity following delivery to mice by S.C. and I.N. routes of administration, supporting the further development of Ad-based vaccines against COVID-19 and other infectious diseases for sustainable global immunization programs.

Impact of backbone linkage positions on the molecular aggregation behavior of polymer photovoltaic materials.

It is imperative to advance the structural design of conjugated materials to achieve a practical impact on the performance of photovoltaic devices. However, the effect of the linkage positions (meta-, para-) of the backbone on the molecular packing has been relatively little explored. In this study, we have synthesized two wide-bandgap polymer photovoltaic materials from identical monomers with different linkage positions, using dibenzo[c,h][2,6]-naphthyridine-5,11-(6H,12H)-dione (DBND) as the building block. This study shows that the para-connected polymer exhibits an unexpected 0.2 eV higher ionization potential and a resultant higher open-circuit voltage than the meta-connected counterpart. We found that different linkage positions result in different intermolecular binding energies and molecular aggregation conformations, leading to different HOMO energy levels and photovoltaic performances. Specifically, theoretical calculations and 2D-NMR indicate that P(p-DBND-f-2T) performs a segregated stacking of f-2T and DBND units, while P(m-DBND-f-2T) films form π-overlaps between f-2T and DBND. These results show that linkage position adjustment on the polymeric backbone exerts a profound influence on the molecular aggregation of the materials. Also, the effect of isomerism on the polymer backbone is crucial in designing polymer structures for photovoltaic applications.

Simultaneous analysis of amino acids based on discriminative 19F NMR spectroscopy.

The simultaneous analysis of amino acids (AAs) is crucial for human health, diagnosis and treatment of disease, and nutritional quality evaluation in foodstuffs. Here, we establish an easy and rapid method for the simultaneous analysis of AAs using a single reagent 2-(trifluoromethyl)benzaldehyde (oTFMBA) based on spectral-separation-enabled 19F NMR spectroscopy. oTFMBA, a highly sensitive chemosensor, is capable of analyzing 19 proteinogenic AAs or non-amino acid amines (non-AAs) in a complex mixture by adjusting the pH in a toilless way. The 19F signals of oTFMBA-labeled AAs are distributed over a wide range of ∼ 0.7 ppm, demonstrating oTFMBA with higher resolution for simultaneous analysis of AAs compared to the o-phthaldialdehyde (OPA) method (<0.6 ppm). Additionally, 12 AAs were unambiguously identified in human urine, including Asp, Ser, Gly, Thr, Glu, Arg, Ala, Val, Ile, Tyr, His, and Phe. Furthermore, our method's detection limit for AAs is 5.83 µM, illustrating sensitivity with an ∼100-fold improvement over the OPA method. This work represents an approach to the analysis of AAs or non-AAs in a complicated mixture (even biofluid) using a 19F NMR probe with high sensitivity, which is of great significance for the simultaneous analysis of multiple analytes.

Application of aromatic amide-derived atropisomers as chiral solvating agents for discrimination of optically active mandelic acid derivatives in 1 H nuclear magnetic resonance spectroscopy.

Non-biaryl atropisomers and their stereochemistry have attracted much attentions in the past years. However, application of the non-biaryl atropisomers as chiral solvating agents is yet to be explored. In this work, four aromatic amide-derived atropisomeric phosphine ligands (hosts) were used as chiral solvating agents to recognize various mandelic acid derivatives (guests) in 1 H nuclear magnetic resonance (NMR) spectroscopy. It is found that chiral center configurations of the four hosts have different effects on the enantiorecognition to the used guests. In addition, the host and guest interaction was further investigated by determination of the host-guest complex stoichiometry using the Job's method and density functional theory calculation, respectively. Moreover, chiral analysis accuracy of these hosts was evaluated through relationship between enantiomeric excess values of 4-chloromandelic acid provided by NMR and gravimetry, respectively.

Determination of tautomeric preference of fenobam in solution by high-resolution NMR spectroscopy.

In this work, tautomeric preference of fenobam in solution was investigated by homonuclear and heteronuclear solution nuclear magnetic resonance (NMR) spectroscopy. 1 H-1 H nuclear Overhauser effect spectroscopy (NOESY) spectrum revealed that fenobam in liquid state exists exclusively in one of the two possible tautomeric structures, which was confirmed by 1 H-13 C HSQC and heteronuclear multiple bond correlation (HMBC) spectra. Moreover, difference between the two tautomeric structures was studied by theoretical calculations, which further proved the result obtained by the NMR experiments.

Selective oxidation of aliphatic C-H bonds in alkylphenols by a chemomimetic biocatalytic system.

Selective oxidation of aliphatic C-H bonds in alkylphenols serves significant roles not only in generation of functionalized intermediates that can be used to synthesize diverse downstream chemical products, but also in biological degradation of these environmentally hazardous compounds. Chemo-, regio-, and stereoselectivity; controllability; and environmental impact represent the major challenges for chemical oxidation of alkylphenols. Here, we report the development of a unique chemomimetic biocatalytic system originated from the Gram-positive bacterium Corynebacterium glutamicum The system consisting of CreHI (for installation of a phosphate directing/anchoring group), CreJEF/CreG/CreC (for oxidation of alkylphenols), and CreD (for directing/anchoring group offloading) is able to selectively oxidize the aliphatic C-H bonds of p- and m-alkylated phenols in a controllable manner. Moreover, the crystal structures of the central P450 biocatalyst CreJ in complex with two representative substrates provide significant structural insights into its substrate flexibility and reaction selectivity.

Eluent Tolerance and Enantioseparation Recovery of Chiral Packing Materials Based on Chitosan Bis(Phenylcarbamate)-(n-Octyl Urea)s for High Performance Liquid Chromatography.

The goal of the present work was to study the influence of the swelling of chitosan derivatives on the enantioseparation and the separation performance recovery of chiral stationary phases (CSPs) based on these derivatives. Therefore, six chitosan bis(phenylcarbamate)-(n-octyl urea)s were synthesized, which were coated on macroporous 3-aminopropyl silica gel affording new CSPs. Most of the CSPs demonstrated strong enantioseparation capability for the tested chiral compounds. The swelling capacity of the chitosan bis(phenylcarbamate)-(n-octyl urea)s in ethyl acetate, acetone and tetrahydrofuran (THF) was evaluated. Among the chitosan derivatives, the chitosan bis(3,5-dichlorophenylcarbamate)-(n-octyl urea) polymer showed the highest swelling capacity in ethyl acetate and THF. The polymer-based CSPs could be utilized with pure ethyl acetate and a normal phase containing 70% THF, but was damaged by pure THF. On the other hand, the separation performance of the damaged CSP could be recovered after it was allowed to stand for a period of time. The observations are important for the development and application of polysaccharide derivative-based CSPs.

Functional characterization of MpaG', the O-methyltransferase involved in the biosynthesis of mycophenolic acid.

Mycophenolic acid (MPA, 1) is a clinically important immunosuppressant. In this report, a gene cluster mpa' responsible for the biosynthesis of 1 was identified from Penicillium brevicompactum NRRL 864. The S-adenosyl-L-methionine-dependent (SAM-dependent) O-methyltransferase encoded by the mpaG' gene was functionally and kinetically characterized in vitro. MpaG' catalyzes the methylation of demethylmycophenolic acid (DMMPA, 6) to form 1. It also showed significant substrate flexibility by methylating two structural derivatives of 6 prepared by organic synthesis.

Ultrasound-mediated method for rapid delivery of nano-particles into cells for intracellular surface-enhanced Raman spectroscopy and cancer cell screening.

Surface-enhanced Raman spectroscopy (SERS) is a powerful technology for providing finger-printing information of cells. A big challenge has been the long time duration and inefficient uptake of metal nano-particles into living cells as substrate for SERS analysis. Herein, a simple method (based on ultrasound) for the rapid transfer of silver nanoparticles (NPs) into living cells for intracellular SERS spectroscopy was presented. In this study, the ultrasound-mediated method for NP delivery overcame the shortcoming of 'passive uptake', and achieved quick acquisition of reproducible SERS spectra from living human nasopharyngeal carcinoma cell lines (C666 and CNE1) and normal nasopharyngeal cell line (NP69). Tentative assignment of the Raman bands in the measured SERS spectra showed cancer cell specific biomolecular differences, including significantly lower DNA concentrations and higher protein concentrations in cancerous nasopharyngeal cells as compared to those of normal cells. Combined with PCA-LDA multivariate analysis, ultrasound-mediated cell SERS spectroscopy differentiated the cancerous cells from the normal nasopharyngeal cells with high diagnostic accuracy (98.7%), demonstrating great potential for high-throughput cancer cell screening applications.

New reactions and products resulting from alternative interactions between the P450 enzyme and redox partners.

Cytochrome P450 enzymes are capable of catalyzing a great variety of synthetically useful reactions such as selective C-H functionalization. Surrogate redox partners are widely used for reconstitution of P450 activity based on the assumption that the choice of these auxiliary proteins or their mode of action does not affect the type and selectivity of reactions catalyzed by P450s. Herein, we present an exceptional example to challenge this postulate. MycG, a multifunctional biosynthetic P450 monooxygenase responsible for hydroxylation and epoxidation of 16-membered ring macrolide mycinamicins, is shown to catalyze the unnatural N-demethylation(s) of a range of mycinamicin substrates when partnered with the free Rhodococcus reductase domain RhFRED or the engineered Rhodococcus-spinach hybrid reductase RhFRED-Fdx. By contrast, MycG fused with the RhFRED or RhFRED-Fdx reductase domain mediates only physiological oxidations. This finding highlights the larger potential role of variant redox partner protein-protein interactions in modulating the catalytic activity of P450 enzymes.

Evaluation of the separation performance of polyvinylpyrrolidone as a virtual stationary phase for chromatographic NMR.

Polyvinylpyrrolidone (PVP) was used as a virtual stationary phase to separate p-xylene, benzyl alcohol, and p-methylphenol by the chromatographic NMR technique. The effects of concentration and weight-average molecular weight (Mw) of PVP, solvent viscosity, solvent polarity, and sample temperature on the resolution of these components were investigated. It was found that both higher PVP concentration and higher PVP Mw caused the increase of diffusion resolution for the three components. Moreover, the diffusion resolution did not change at viscosity-higher solvents. Moreover, the three components showed different resolution at different solvents. As temperature increased, the diffusion resolution between p-xylene and benzyl alcohol gradually increased, and the one between p-xylene and p-methylphenol slightly increased from 278 to 298 K and then decreased above 298 K. It was also found that the polarity of the analytes played an important role for the separation by affecting the diffusion coefficient.

Polydimethylsiloxane: a general matrix for high-performance chromatographic NMR spectroscopy.

The detection and structural characterization of the components of a mixture is a challenging task. Therefore, the development of a facile and general method that enables both the separation and the structural characterization of the components is desired. Diffusion-ordered NMR spectroscopy (DOSY) with the aid of a matrix is a promising tool for this purpose. However, because the currently existing matrices only separate limited components, the application of the DOSY technique is restricted. Herein we introduce a new versatile matrix, poly(dimethylsiloxane), which can fully separate many mixtures of different structural types by liquid-state NMR spectroscopy. With poly(dimethylsiloxane), liquid-state chromatographic NMR spectroscopy could become a general approach for the structural elucidation of mixtures of compounds.

Irreversible denaturation of proteins through aluminum-induced formation of backbone ring structures.

A combination of ab initio calculations, circular dichroism, nuclear magnetic resonance, and X-ray photoelectron spectroscopy has shown that aluminum ions can induce the formation of backbone ring structures in a wide range of peptides, including neurodegenerative disease related motifs. These ring structures greatly destabilize the protein and result in irreversible denaturation. This behavior benefits from the ability of aluminum ions to form chemical bonds simultaneously with the amide nitrogen and carbonyl oxygen atoms on the peptide backbone.