Distinct Characteristic Binding Modes of Benzofuran Core Inhibitors to Diverse Genotypes of Hepatitis C Virus NS5B Polymerase: A Molecular Simulation Study.

The benzofuran core inhibitors HCV-796, BMS-929075, MK-8876, compound 2, and compound 9B exhibit good pan-genotypic activity against various genotypes of NS5B polymerase. To elucidate their mechanism of action, multiple molecular simulation methods were used to investigate the complex systems of these inhibitors binding to GT1a, 1b, 2a, and 2b NS5B polymerases. The calculation results indicated that these five inhibitors can not only interact with the residues in the palm II subdomain of NS5B polymerase, but also with the residues in the palm I subdomain or the palm I/III overlap region. Interestingly, the binding of inhibitors with longer substituents at the C5 position (BMS-929075, MK-8876, compound 2, and compound 9B) to the GT1a and 2b NS5B polymerases exhibits different binding patterns compared to the binding to the GT1b and 2a NS5B polymerases. The interactions between the para-fluorophenyl groups at the C2 positions of the inhibitors and the residues at the binding pockets, together with the interactions between the substituents at the C5 positions and the residues at the reverse ß-fold (residues 441-456), play a key role in recognition and the induction of the binding. The relevant studies could provide valuable information for further research and development of novel anti-HCV benzofuran core pan-genotypic inhibitors.

Lysine-Specific Demethylase 1 Inhibitors: A Comprehensive Review Utilizing Computer-Aided Drug Design Technologies.

Lysine-specific demethylase 1 (LSD1/KDM1A) has emerged as a promising therapeutic target for treating various cancers (such as breast cancer, liver cancer, etc.) and other diseases (blood diseases, cardiovascular diseases, etc.), owing to its observed overexpression, thereby presenting significant opportunities in drug development. Since its discovery in 2004, extensive research has been conducted on LSD1 inhibitors, with notable contributions from computational approaches. This review systematically summarizes LSD1 inhibitors investigated through computer-aided drug design (CADD) technologies since 2010, showcasing a diverse range of chemical scaffolds, including phenelzine derivatives, tranylcypromine (abbreviated as TCP or 2-PCPA) derivatives, nitrogen-containing heterocyclic (pyridine, pyrimidine, azole, thieno[3,2-b]pyrrole, indole, quinoline and benzoxazole) derivatives, natural products (including sanguinarine, phenolic compounds and resveratrol derivatives, flavonoids and other natural products) and others (including thiourea compounds, Fenoldopam and Raloxifene, (4-cyanophenyl)glycine derivatives, propargylamine and benzohydrazide derivatives and inhibitors discovered through AI techniques). Computational techniques, such as virtual screening, molecular docking and 3D-QSAR models, have played a pivotal role in elucidating the interactions between these inhibitors and LSD1. Moreover, the integration of cutting-edge technologies such as artificial intelligence holds promise in facilitating the discovery of novel LSD1 inhibitors. The comprehensive insights presented in this review aim to provide valuable information for advancing further research on LSD1 inhibitors.

Unraveling the Binding Mode of Cyclic Adenosine-Inosine Monophosphate (cAIMP) to STING through Molecular Dynamics Simulations.

The stimulator of interferon genes (STING) plays a significant role in immune defense and protection against tumor proliferation. Many cyclic dinucleotide (CDN) analogues have been reported to regulate its activity, but the dynamic process involved when the ligands activate STING remains unclear. In this work, all-atom molecular dynamics simulations were performed to explore the binding mode between human STING (hSTING) and four cyclic adenosine-inosine monophosphate analogs (cAIMPs), as well as 2',3'-cGMP-AMP (2',3'-cGAMP). The results indicate that these cAIMPs adopt a U-shaped configuration within the binding pocket, forming extensive non-covalent interaction networks with hSTING. These interactions play a significant role in augmenting the binding, particularly in interactions with Tyr167, Arg238, Thr263, and Thr267. Additionally, the presence of hydrophobic interactions between the ligand and the receptor further contributes to the overall stability of the binding. In this work, the conformational changes in hSTING upon binding these cAIMPs were also studied and a significant tendency for hSTING to shift from open to closed state was observed after binding some of the cAIMP ligands.

Polarity Conversion of the Ag2S/AgInS2 Heterojunction by Radical-Induced Positive Feedback Polydopamine Adhesion for Signal-Switchable Photoelectrochemical Biosensing.

Efficient tuning of the polarity of photoactive nanomaterials is of great importance in improving the performance of photoelectrochemical (PEC) sensing platforms. Herein, polarity of the Ag2S/AgInS2 heterojunction is converted by radical-induced positive feedback polydopamine (PDA) adhesion, which is further employed to develop a signal-switchable PEC biosensor. In the nanocomposites, Ag2S and AgInS2 achieve electron-hole separation, exhibiting a strong anodic PEC response. Under the irradiation of light, the Ag2S/AgInS2 heterojunction is able to produce superoxide radical and hydroxyl radical intermediate species, leading to the polymerization of dopamine (DA) and the subsequent adhesion of PDA onto the Ag2S/AgInS2 heterojunction (Ag2S/AgInS2@PDA). By constructing a new electron-transfer pathway with PDA, the polarity of the Ag2S/AgInS2 heterojunction is converted, and the PEC response changes from anodic to cathodic photocurrents. In addition, since the photoreduction activity of PDA is stronger than that of the Ag2S/AgInS2 heterojunction, more superoxide radical can be produced by Ag2S/AgInS2@PDA once PDA is generated, thereby promoting the generation of PDA. Consequently, a positive feedback mechanism is established to enhance the polarity conversion of the Ag2S/AgInS2 heterojunction and amplify the responding to DA. As a result, the bioanalytical method is capable of sensitively quantifying DA in 10 orders of magnitude with an ultralow limit of detection. Moreover, the applicability of this biosensor in real samples is identified by measuring DA in fetal bovine serum and compared with a commercial ELISA method. Overall, this work offers an alternative perspective for adjusting photogenerated carriers of nanomaterials and designing high-performance PEC biosensors.

Single-cell transcriptome, phagocytic activity and immunohistochemical analysis of crucian carp (Carassius auratus) in response to Rahnella aquatilis infection.

In teleost fish, kidney is an important immune and hematopoietic organ with multiple physiological functions. However, the immune cells and cellular markers of kidney require further elucidation in crucian carp (C. auratus). Here we report on the single-cell transcriptional landscape in posterior kidney, immunohistochemical and phagocytic features of C. auratus with R. aquatilis infection. The results showed that a total of 18 cell populations were identified for the main immune cells such as monocytes/macrophages (Mo/Mφ), dendritic cells (DCs), B cells, T cells, granulocytes and hematopoietic progenitor cells (HPCs). Pseudo-time trajectory analysis was reconstructed for the immune cells using Monocle2 to obtain additional insights into their developmental lineage relationships. In the detected tissues (liver, spleen, kidney, intestine, skin, and gills) of infected fish exhibited positive immunohistochemical staining with prepared for antibody to R. aquatilis. Apoptotic cells were fluorescently demonstrated by TUNEL assay, and bacterial phagocytic activity were observed for neutrophils and Mo/Mφ cells, respectively. Moreover, a similar up-ward/down-ward expression trend of the selected immune and inflammatory genes was found in the kidney against R. aquatilis infection, which were significantly involved in TLR/NLR, ECM adhesion, phago-lysosome, apoptosis, complement and coagulation pathways. To our knowledge, this is the first report on the detailed characterization of immune cells and host-R. aquatilis interaction, which will contribute to understanding on the biology of renal immune cells and repertoire of potential markers in cyprinid fish species.

Single-cell RNA analysis of chemokine expression in heterogeneous CD14+ monocytes with lipopolysaccharide-induced bone resorption.

Lipopolysaccharide (LPS)-induced bone resorption has normally been found in inflammatory bone diseases, but the underlying mechanism is currently unclear. Since LPS binds to CD14 and activates Toll-like receptor 4 (TLR4) in monocytes, the present study focused on CD14+ monocytes and observed their responses after LPS treatment during the progression of local bone destruction. CD14+ monocytes were obtained from human peripheral blood mononuclear cells (PBMCs) by magnetic cell separation (MACS), and their classification was confirmed by fluorescence-activated cell sorting (FACS). Single-cell RNA sequencing (scRNA-seq) was further utilized to analyze their subpopulations, and the results showed that physiological CD14+ monocytes were heterogeneous and divided into 6 subsets, that could be easily agitated. After priming with a suitable concentration of LPS, heterogeneous CD14+ monocytes became pathological and expressed a large number of chemokines as a "cascade effect". Some of these chemokines have been validated in an animal model of mouse calvarial bone invasion. Taken together, our research has linked enhanced chemokine expression with stimulation of heterogeneous CD14+ monocytes, and indicated that inflammatory responses caused by microbiome infection are responsible for the recruitment and mobilization of CD14+ monocytes into bone resorption sites, which may explain the pathogenesis of LPS-associated bone diseases.

A compositional mediation model for a binary outcome: Application to microbiome studies.

MOTIVATION: The delicate balance of the microbiome is implicated in our health and is shaped by external factors, such as diet and xenobiotics. Therefore, understanding the role of the microbiome in linking external factors and our health conditions is crucial to translate microbiome research into therapeutic and preventative applications. RESULTS: We introduced a sparse compositional mediation model for binary outcomes to estimate and test the mediation effects of the microbiome utilizing the compositional algebra defined in the simplex space and a linear zero-sum constraint on probit regression coefficients. For this model with the standard causal assumptions, we showed that both the causal direct and indirect effects are identifiable. We further developed a method for sensitivity analysis for the assumption of the no unmeasured confounding effects between the mediator and the outcome. We conducted extensive simulation studies to assess the performance of the proposed method and applied it to real microbiome data to study mediation effects of the microbiome on linking fat intake to overweight/obesity. AVAILABILITY AND IMPLEMENTATION: An R package can be downloaded from https://github.com/mbsohn/cmmb. SUPPLEMENTARY INFORMATION: Supplementary files are available at Bioinformatics online.

Notch signaling dependent monocyte conversion alleviates immune-mediated neuropathies by regulating RBP-J/NR4A1 axis.

Monocytes in peripheral blood and sciatic nerves play vital roles in immune-mediated neuropathies such as Guillain-Barré syndrome (GBS). Different subpopulations of monocytes, including classical and non-classical, exhibit distinct functions as well as phenotypic conversion potentials. However, the mechanisms underlying their development during immune-mediated neuropathy remain unclear. Notch signaling participates in monocyte differentiation and function. In this study, we used a myeloid-specific Notch signaling activation transgenic mouse (NICcA) and investigated the role of Notch signaling in monocytes during experimental autoimmune neuritis (EAN) in a mouse model of GBS. Clinical score assessment and histopathological examination revealed that sciatic nerve injury was attenuated in NICcA EAN mice compared to that in control mice. Flow cytometry and immunofluorescence staining suggested that increasing Ly6Clo monocytes in the peripheral blood and nerve tissue might contribute to the alleviation of neuritis in NICcA mice. Meanwhile, an in vitro study suggested that bone marrow-derived monocytes from NICcA mice are more inclined toward Ly6Clo cells than Ly6Chi cells. Differential expression of monocyte development-associated genes was detected in NICcA and wild-type mice using RNA sequencing. The expression of Nr4a1 is upregulated remarkably when Notch signaling is activated. Treatment with Nr4a1 antagonist on NICcA mice-derived monocytes compromise their Ly6Clo tendency. Consistently, a relationship between monocyte conversion and disease severity was observed in blood samples from patients with GBS. In conclusion, our current study showed that monocyte conversion modulated by Notch signaling plays an essential role in the EAN mouse model.

ReLMole: Molecular Representation Learning Based on Two-Level Graph Similarities.

Molecular representation is a critical part of various prediction tasks for physicochemical properties of molecules and drug design. As graph notations are common in expressing the structural information of chemical compounds, graph neural networks (GNNs) have become the mainstream backbone model for learning molecular representation. However, the scarcity of task-specific labels in the biomedical domain limits the power of GNNs. Recently, self-supervised pretraining for GNNs has been leveraged to deal with this issue, while the existing pretraining methods are mainly designed for graph data in general domains without considering the specific data properties of molecules. In this paper, we propose a representation learning method for molecular graphs, called ReLMole, which is featured by a hierarchical graph modeling of molecules and a contrastive learning scheme based on two-level graph similarities. We assess the performance of ReLMole on two types of downstream tasks, namely, the prediction of molecular properties (MPs) and drug-drug interaction (DDIs). ReLMole achieves promising results for all the tasks. It outperforms the baseline models by over 2.6% on ROC-AUC averaged across six MP prediction tasks, and it improves the F1 value by 7-18% in DDI prediction for unseen drugs compared with other self-supervised models.

Comparing algorithms for characterizing treatment effect heterogeneity in randomized trials.

The identification and estimation of heterogeneous treatment effects in biomedical clinical trials are challenging, because trials are typically planned to assess the treatment effect in the overall trial population. Nevertheless, the identification of how the treatment effect may vary across subgroups is of major importance for drug development. In this work, we review some existing simulation work and perform a simulation study to evaluate recent methods for identifying and estimating the heterogeneous treatments effects using various metrics and scenarios relevant for drug development. Our focus is not only on a comparison of the methods in general, but on how well these methods perform in simulation scenarios that reflect real clinical trials. We provide the R package benchtm that can be used to simulate synthetic biomarker distributions based on real clinical trial data and to create interpretable scenarios to benchmark methods for identification and estimation of treatment effect heterogeneity.

Design Two Novel Tetrahydroquinoline Derivatives against Anticancer Target LSD1 with 3D-QSAR Model and Molecular Simulation.

Lysine-specific demethylase 1 (LSD1) is a histone-modifying enzyme, which is a significant target for anticancer drug research. In this work, 40 reported tetrahydroquinoline-derivative inhibitors targeting LSD1 were studied to establish the three-dimensional quantitative structure-activity relationship (3D-QSAR). The established models CoMFA (Comparative Molecular Field Analysis (q2 = 0.778, Rpred2 = 0.709)) and CoMSIA (Comparative Molecular Similarity Index Analysis (q2 = 0.764, Rpred2 = 0.713)) yielded good statistical and predictive properties. Based on the corresponding contour maps, seven novel tetrahydroquinoline derivatives were designed. For more information, three of the compounds (D1, D4, and Z17) and the template molecule 18x were explored with molecular dynamics simulations, binding free energy calculations by MM/PBSA method as well as the ADME (absorption, distribution, metabolism, and excretion) prediction. The results suggested that D1, D4, and Z17 performed better than template molecule 18x due to the introduction of the amino and hydrophobic groups, especially for the D1 and D4, which will provide guidance for the design of LSD1 inhibitors.

Antibiotics and microbial community-induced antibiotic-resistant genes distribution in soil and sediment in the eastern coastline of China.

The health risk of antibiotic-resistant genes (ARGs) has been a global concern, while the report on occurrence and prevalence of ARGs in coastal zone is relatively scarce. This study investigated typical ARGs in soil and sediment in coastal line of eastern China and assessed its relationship with antibiotics and heavy metals as well as microbial community. Results showed that eight ARGs were all detected in the samples, and ß-lactam resistance gene blaTEM reached the highest absolute abundance (6.28 × 107 ~ 6.48 × 108 copies/g) and relative abundance (2.3 × 10-2 copies/16S rRNA) among samples. Amoxicillin and tetracycline were most frequently detected with the average concentration of 2.28 µg/kg and 3.48 µg/kg, respectively. Cr and Zn were found to be most abundant heavy metals with average value of 82.1 and 59.1 mg/kg, respectively. Proteobacteria, Campilobacterota, Bacteroidota, and Firmicutes were dominant phyla in most samples, while bacterial community varied significantly among samples. Redundancy analyses (RDA) showed that microbial community and antibiotics (amoxicillin and tetracycline) were driving factors of ARGs distribution, while heavy metals were not significantly correlated with ARGs. This study is helpful to understand the fate of ARGs in coastal zone.

C(sp3 )-H Hydroxylation in Diiron ß-Hydroxylase CmlA Transpires by Amine-Assisted O2 Activation Avoiding FeIV 2 O2 Species.

Through QM/MM modeling, we discovered that C(sp3 )-H ß-hydroxylation in the diiron hydroxylase CmlA transpires by traceless amine-assisted O2 activation. Different from the canonical diiron hydroxylase sMMO, this aliphatic-amine-assisted O2 activation avoids generating the high-valent diferryl FeIV 2 O2 species, but alternatively renders a diferric FeIII 2 O species as the reactive oxidant. From this unprecedented O2 activation mode, the derived C(sp3 )-H hydroxylation mechanism in CmlA also differs drastically from the toluene aromatic C(sp2 )-H hydroxylation in the diiron hydroxylase T4MO. This substrate-modulated O2 activation in CmlA has rich mechanistic implications for other diiron hydroxylases with an amine group adjacent to the C-H bond under hydroxylation in substrates, such as hDOHH. Furthermore, the adapted coordination environment of the diiron cofactor upon O2 binding in CmlA opens up more structural and mechanistic possibilities for O2 activation in non-heme diiron enzymes.

Lysinibacillus agricola sp. nov., isolated from soil.

A gram-staining-positive, rod-shaped bacterium, designed strain FJAT-51161T was isolated from farmland soil collected from Fujian Province, China. Growth was observed at 25-40 °C (optimum 30 °C), pH 7.0-9.0 (optimum 7.0), and NaCl tolerance in the range of 0-7% (w/v), respectively. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the strain FJAT-51161T belonged to the genus Lysinibacillus, and had the closest relationship with Lysinibacillus xylanilyticus XDB9T (99.0% 16S rRNA sequence similarity). The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values based on the genome sequence analysis between strain FJAT-51161T and the closest reference strain were 38.0% for dDDH and 88.7% for ANI, respectively, lower than the prokaryotic species delineation values. Further analysis showed that strain FJAT-51161T shared the fatty acid profiles such as iso-C15:0 (46.7%), iso-C16:0 (15.8%), C16:1 ω7c alcohol (14.0%), anteiso-C15:0 (6.9%) with other members of the genus Lysinibacillus. As the peptidoglycan contained the amino acids alanine, lysine, glycine and aspartic acid, the type A4α was deduced as found in the closest relatives of strain FJAT-51161T. The peptidoglycan of strain FJAT-51161T was L-Lys-D-Asp (type A4α). The main quinone was MK-7 and MK-6. The major polar lipids were diphosphatidylglycerol (DPG) and phosphatidylethanolamine (PE). The DNA G + C content is 36.6 mol%. Based on the phenotypic characters and taxono-genomics study, strain FJAT-51161T is considered to represent a novel Lysinibacillus species, for which the name Lysinibacillus agricola sp. nov. is proposed. The type strain is FJAT-51161T (GDMCC1.2350T = KCTC 43326T).

Clinical features, treatment and prognosis of MuSK antibody-associated myasthenia gravis in Northwest China: a single-centre retrospective cohort study.

BACKGROUND AND PURPOSE: To summarize the clinical characteristics of patients with muscle-specific kinase antibody-associated myasthenia gravis (MuSK-MG) and to evaluate the therapeutic responses to different treatment regimes. METHODS: Eighteen MuSK-MG patients admitted in our department between October 2017 and September 2020 were included. Clinical parameters were collected and the responses to different immunosuppressive drugs were assessed by MGFA Postintervention Status (MGFA-PIS). Meanwhile, the correlation between QMG scores and MuSK antibody titers were analyzed and MuSK antibody (MuSK-ab) titers were compared before and after therapy based on different immunosuppressive treatment regimes. RESULTS: Female predominance (ratio of females to males, 15:3) was evident in the study population, with the average onset age of (40.28 ± 18.57) years and the median disease course of 30.50 months (interquartile range [IQR], 17.50-44.75 months). Ocular manifestation was the most common onset symptom (11/18; 61.11%), and mild symmetrical ptosis was most frequent. Bulbar symptoms had the highest incidence of 88.89% over the entire disease course. Abnormal responses to RNS test were recorded most frequently on the musculus deltoideus (83.33%). All patients were treated with prednisone (Pred) alone or plus azathioprine (AZA), tacrolimus (TAC) or low-dose rituximab (RTX), and 17 (94.44%) of them achieved a favorable outcome defined as minimal manifestation (MM) or better. In general, an obvious positive correlation between QMG score and MuSK-ab titer (r = 0.710, P < 0.001) were found in all patients. A more significant reduction of MuSK-ab titers was observed in patients receiving TAC or RTX plus Pred than those receiving AZA plus Pred. CONCLUSIONS: The prominent clinical manifestations of ocular and bulbar muscles involvements, together with abnormal RNS response mostly recorded on the musculus deltoideus and better efficacy associated with TAC or low-dose RTX plus Pred, provide a more exhaustive picture of MuSK-MG, particularly in Northwest China.

Generalized linear models with linear constraints for microbiome compositional data.

Motivated by regression analysis for microbiome compositional data, this article considers generalized linear regression analysis with compositional covariates, where a group of linear constraints on regression coefficients are imposed to account for the compositional nature of the data and to achieve subcompositional coherence. A penalized likelihood estimation procedure using a generalized accelerated proximal gradient method is developed to efficiently estimate the regression coefficients. A de-biased procedure is developed to obtain asymptotically unbiased and normally distributed estimates, which leads to valid confidence intervals of the regression coefficients. Simulations results show the correctness of the coverage probability of the confidence intervals and smaller variances of the estimates when the appropriate linear constraints are imposed. The methods are illustrated by a microbiome study in order to identify bacterial species that are associated with inflammatory bowel disease (IBD) and to predict IBD using fecal microbiome.

Mechanistic insights into ring cleavage of hydroquinone by PnpCD from quantum mechanical/molecular mechanical calculations.

PnpCD is a mononuclear non-heme iron(ii) dioxygenase containing an unusual 2His-1Glu-1Asn metal-binding motif. To gain insights into the catalytic mechanism of the ring opening of hydroquinone by PnpCD, hybrid quantum mechanics/molecular mechanics calculations have been performed by using two models with different protonation states of the substrate (nonionized and ionized forms of the Fe-bound hydroxyl group of hydroquinone). In both cases, the structure of the reactive Fe-O2 species reveals a trigonal bipyramidal complex, in which Asn258 is no longer coordinated to the iron center. The catalytic process mainly involves the attack of the superoxo radical, O-O bond cleavage, three-membered ring closure and opening, attack of the Fe-bound oxyl radical, and ring-opening of the seven-membered ring. The transition state for the peroxo O-O bond cleavage was found to be the rate-determining transition state. The second-sphere Glu248 serves as a proton acceptor to deprotonate the unbound substrate hydroxyl group, thereby facilitating the electron transfer between the substrate and dioxygen. The first-sphere Glu262 can act as an acid-base catalyst to lower the rate-limiting barrier, thus providing a useful clue for improving catalytic efficiency.

Mechanistic insights into a non-heme 2-oxoglutarate-dependent ethylene-forming enzyme: selectivity of ethylene-formation versusl-Arg hydroxylation.

The ethylene-forming enzyme (EFE) is a unique member of the Fe(ii)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenases. It converts 2OG into ethylene plus three CO2 molecules (ethylene-forming reaction) and also catalyzes the C5 hydroxylation of l-arginine coupled to the oxidative decarboxylation of 2OG (l-Arg hydroxylation reaction). To uncover the mechanisms of the dual transformations by EFE, quantum mechanical/molecular mechanical (QM/MM) calculations were carried out. Based on the results, a branched mechanism was proposed. An FeII-peroxysuccinate complex with a dissociated CO2 generated through the nucleophilic attack of the superoxo moiety of the Fe-O2 species on the keto carbon of 2OG is the key common intermediate in both reactions. A competition between the subsequent CO2 insertion (a key step in the ethylene-forming pathway) and the O-O bond cleavage (leading to the formation of succinate) governs the product selectivity. The calculated reaction barriers suggested that the CO2 insertion is favored over the O-O bond cleavage. This is consistent with the product preference observed in experiments. By comparison with the results of AsqJ (an Fe/2OG oxygenase that leads to substrate oxidation exclusively), the protein environment was found to be crucial for the selectivity. Further calculations demonstrated that the local electric field of the protein environment in EFE promotes ethylene formation by acting as a charge template, exemplifying the importance of the electrostatic interaction in enzyme catalysis. These findings offer mechanistic insights into the EFE catalysis and provide important clues for better understanding the unique ethylene-forming capability of EFE compared with other Fe/2OG oxygenases.

Origin of Nitric Oxide Reduction Activity in Flavo-Diiron NO Reductase: Key Roles of the Second Coordination Sphere.

The second coordination sphere constitutes a distinguishing factor in the active site to modulate enzymatic reactivity. To unravel the origin of NO-to-N2 O reduction activity of non-heme diiron enzymes, herein we report a strong second-coordination-sphere interaction between a conserved Tyr197 and the key iron-nitrosyl intermediate of Tm FDP (flavo-diiron protein), which leads to decreased reaction barriers towards N-N formation and N-O cleavage in NO reduction. This finding supports the direct coupling of diiron dinitrosyl as the N-N formation mode in our QM/MM modeling, and reconciles the mechanistic controversy of external reduction between FDPs and synthetic biomimetics of the iron-nitrosyls. This work highlights the application of QM/MM 57 Fe Mössbauer modeling in elucidating the structural features of not only first, but also second coordination spheres of the key transient species involved in NO/O2 activation by non-heme diiron enzymes.

Intracranial lesion as onset symptom in a patient with early undifferentiated connective tissue disease: a case report.

BACKGROUND: Undifferentiated connective tissue disease (UCTD) is widely considered to be a distinct clinical entity, and now divided into two subgroups: stable UCTD and early UCTD. The most frequent onset symptoms of UCTD include arthralgias, arthritis, Raynaud's phenomenon, mucocutaneous involvement, and sicca symptoms. However, Neurologic involvement is rare, and intracranial lesion as onset symptom in a patient with early UCTD has not yet been reported. CASE PRESENTATION: A 51-year-old Chinese female experienced progressive left leg weakness for 14 days before hospitalizing in our department. The lesion on right parietal lobe was initially detected by brain magnetic resonance imaging. Although the patient declined a cerebral biopsy, the possibility of stroke, cerebral venous sinus thrombosis, NMOSD, MS, autoimmune encephalitis, intracranial infections, and malignant tumors as cause of the lesion was excluded by intracranial angiogram, CSF study, MRI enhancement and MRS examination. Moreover, immunologic studies showed high titer of antinuclear antibody, increased erythrocyte sedimentation rate and C-reactive protein. These results led to a diagnosis of early UCTD with central nerve system (CNS) involvement. After low dose corticosteroid and azathioprine therapy, the patient's symptoms, abnormalities in immunologic tests and cerebral radiologic examinations were all greatly improved within a short duration. CONCLUSIONS: This is the first report of intracranial lesion as onset symptom in a patient with early UCTD. Our case suggested that central nerve system (CNS) involvement could be the onset symptom in early UCTD, and should be recognized quickly with exclusion of other causative factors in the differential diagnosis. Prompt and adequate treatment with low-dose steroid and immunosuppressive drugs could improve the prognosis of both early UCTD and CNS involvement.