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乙酰氯 溶液 1 M in methylene chloride; CAS Number: 75-36-5; find Sigma-Aldrich-708496 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich

乙酰氯 溶液 1 M in methylene chloride | Sigma-Aldrich

乙酰氯 溶液 1&#160;M in methylene chloride

乙酰氯 溶液

New phenylfluorenyl based linkers for solid phase synthesis

Solid phase synthesis of styrylquinazolinones

Selective synthesis of spirooxindoles via a two-step reaction of N-phenacylpyridinium bromide, 1, 3-indanedione and N-alkylisations

A highly efficient procedure for regeneration of carbonyl groups from their corresponding oxathioacetals and dithioacetals using sodium nitrite and acetyl chloride in dichloromethane

Acetyl chloride-mediated mild and chemoselective attachment and removal of tetrahydropyranyl (THP) group

Activated coagulation Factor XII (FXIIa) infusion increases peripheral resistance (TPR) and mean arterial pressure (MAP) of Brown Norway but not plasma kininogen deficient Brown Norway Katholiek (BNK) rats. FXIIa concentrations are elevated in hypertensive end-stage renal disease patients receiving conventional haemodialysis (CHD). Conversion to nocturnal haemodialysis (NHD) lowers peripheral resistance and MAP. To determine whether the plasma coagulation FXIIa-kallikrein-kinin axis contributes to the hypertension of chronic kidney disease (CKD). Plasma FXIIa and haemodynamic data were acquired in 11 CHD patients before and after 2 months of NHD. Cardiac and systemic haemodynamics of Brown Norway and BNK rats rendered hypertensive and uremic by 5/6 nephrectomy (NX) were determined before and after acute FXIIa inhibition. FXIIa was increased three-fold in CHD patients relative to control plasma (P < 0.05). After conversion to NHD, both ΔMAP and ΔTPR correlated with ΔFXIIa. In rats, plasma FXIIa was three-fold higher in both NX groups than respective SHAM controls (all P < 0.05), but MAP (147 ± 4 vs. 133 ± 2 mmHg; P < 0.05) and TPR (2.8 ± 0.2 vs. 2.3 ± 0.2 units; P < 0.05) were greater in Brown Norway NX (n = 16) than in BNK (n = 15) NX rats. FXIIa correlated with MAP only in Brown Norway NX, and plasma catecholamines were increased relative to SHAM only in Brown Norway NX (P < 0.05). In Brown Norway NX rats, FXIIa inhibitor infusion decreased MAP (-12 mmHg) and TPR (-0.5 Units) (both P < 0.05), and halved catecholamines (P < 0.05). No such changes occurred in BNK NX rats. FXIIa-kininogen mediated vasoconstriction contributes significantly to CKD hypertension in Brown Norway rats; this novel mechanism may be active in humans with CKD.

Coagulation factor XIIa-kinin-mediated contribution to hypertension of chronic kidney disease.

Influenza viruses exist as a large group of closely related viral genomes, also called quasispecies. The composition of this influenza viral quasispecies can be determined by an accurate and sensitive sequencing technique and data analysis pipeline. We compared the suitability of two benchtop next-generation sequencers for whole genome influenza A quasispecies analysis: the Illumina MiSeq sequencing-by-synthesis and the Ion Torrent PGM semiconductor sequencing technique. We first compared the accuracy and sensitivity of both sequencers using plasmid DNA and different ratios of wild type and mutant plasmid. Illumina MiSeq sequencing reads were one and a half times more accurate than those of the Ion Torrent PGM. The majority of sequencing errors were substitutions on the Illumina MiSeq and insertions and deletions, mostly in homopolymer regions, on the Ion Torrent PGM. To evaluate the suitability of the two techniques for determining the genome diversity of influenza A virus, we generated plasmid-derived PR8 virus and grew this virus in vitro. We also optimized an RT-PCR protocol to obtain uniform coverage of all eight genomic RNA segments. The sequencing reads obtained with both sequencers could successfully be assembled de novo into the segmented influenza virus genome. After mapping of the reads to the reference genome, we found that the detection limit for reliable recognition of variants in the viral genome required a frequency of 0.5% or higher. This threshold exceeds the background error rate resulting from the RT-PCR reaction and the sequencing method. Most of the variants in the PR8 virus genome were present in hemagglutinin, and these mutations were detected by both sequencers. Our approach underlines the power and limitations of two commonly used next-generation sequencers for the analysis of influenza virus gene diversity. We conclude that the Illumina MiSeq platform is better suited for detecting variant sequences whereas the Ion Torrent PGM platform has a shorter turnaround time. The data analysis pipeline that we propose here will also help to standardize variant calling in small RNA genomes based on next-generation sequencing data.

Analysis of the genetic diversity of influenza A viruses using next-generation DNA sequencing.

Zinc circulates free in plasma at a concentration of 0.1-2 µM, but its levels increase locally when it is released from activated platelets. Although zinc influences many processes in haemostasis, its effect on fibrinolysis has not been thoroughly investigated. Using a fluorescent zinc-binding probe, we demonstrated that zinc binds tissue-type plasminogen activator (tPA) and plasmin with high affinity (Kd values of 0.2 µM), and surface plasmon resonance studies revealed that zinc binds fibrin with a Kd of 12.8 µM. Zinc had no effect on the affinity of plasminogen or plasmin for fibrin, but increased the affinity of tPA by two-fold. In the presence of 5 µM zinc, the catalytic efficiency of plasminogen activation by tPA was reduced by approximately two-fold, both in the absence or presence of fibrin. Zinc attenuated plasmin-mediated degradation of the fibrinogen alpha-chain by 43 %, but had no effect on trypsin degradation. tPA-mediated fibrin clot lysis was prolonged 2.5-fold by zinc in a concentration-dependent fashion, and tPA-mediated plasma clot lysis was attenuated by 1.5-fold. Therefore, our data indicate that zinc modulates fibrinolysis by attenuating tPA-mediated plasminogen activation and plasmin-induced fibrin degradation. These findings suggest that local release of zinc by platelets attenuates fibrinolysis.

Zinc delays clot lysis by attenuating plasminogen activation and plasmin-mediated fibrin degradation.

Anaphylaxis is an acute, potentially lethal, multisystem syndrome resulting from the sudden release of mast cell-derived mediators into the circulation. We report here that a plasma protease cascade, the factor XII-driven contact system, critically contributes to the pathogenesis of anaphylaxis in both murine models and human subjects. Deficiency in or pharmacologic inhibition of factor XII, plasma kallikrein, high-molecular-weight kininogen, or the bradykinin B2 receptor, but not the B1 receptor, largely attenuated allergen/IgE-mediated mast cell hyperresponsiveness in mice. Reconstitutions of factor XII null mice with human factor XII restored susceptibility for allergen/IgE-mediated hypotension. Activated mast cells systemically released heparin, which provided a negatively charged surface for factor XII autoactivation. Activated factor XII generates plasma kallikrein, which proteolyzes kininogen, leading to the liberation of bradykinin. We evaluated the contact system in patients with anaphylaxis. In all 10 plasma samples immunoblotting revealed activation of factor XII, plasma kallikrein, and kininogen during the acute phase of anaphylaxis but not at basal conditions or in healthy control subjects. The severity of anaphylaxis was associated with mast cell degranulation, increased plasma heparin levels, the intensity of contact system activation, and bradykinin formation. In summary, the data collectively show a role of the contact system in patients with anaphylaxis and support the hypothesis that targeting bradykinin generation and signaling provides a novel and alternative treatment strategy for anaphylactic attacks.

Plasma contact system activation drives anaphylaxis in severe mast cell-mediated allergic reactions.

Primary attachment to cellular glycans is a critical entry step for most human viruses. Some viruses, such as herpes simplex virus type 1 (HSV-1) and hepatitis C virus (HCV), bind to heparan sulfate, whereas others, such as influenza A virus (IAV), bind to sialic acid. Receptor mimetics that interfere with these interactions are active against viruses that bind to either heparan sulfate or to sialic acid. However, no molecule that inhibits the attachment of viruses in both groups has yet been identified. Epigallocatechin gallate (EGCG), a green tea catechin, is active against many unrelated viruses, including several that bind to heparan sulfate or to sialic acid. We sought to identify the basis for the broad-spectrum activity of EGCG. Here, we show that EGCG inhibits the infectivity of a diverse group of enveloped and nonenveloped human viruses. EGCG acts directly on the virions, without affecting the fluidity or integrity of the virion envelopes. Instead, EGCG interacts with virion surface proteins to inhibit the attachment of HSV-1, HCV, IAV, vaccinia virus, adenovirus, reovirus, and vesicular stomatitis virus (VSV) virions. We further show that EGCG competes with heparan sulfate for binding of HSV-1 and HCV virions and with sialic acid for binding of IAV virions. Therefore, EGCG inhibits unrelated viruses by a common mechanism. Most importantly, we have identified EGCG as the first broad-spectrum attachment inhibitor. Our results open the possibility for the development of small molecule broad-spectrum antivirals targeting virion attachment. Importance: This study shows that it is possible to develop a small molecule antiviral or microbicide active against the two largest groups of human viruses: those that bind to glycosaminoglycans and those that bind to sialoglycans. This group includes the vast majority of human viruses, including herpes simplex viruses, cytomegalovirus, influenza virus, poxvirus, hepatitis C virus, HIV, and many others.

A small molecule inhibits virion attachment to heparan sulfate- or sialic acid-containing glycans.

Sequence-defined macromolecules consist of a defined chain length (single mass), end-groups, composition and topology and prove promising in application fields such as anti-counterfeiting, biological mimicking and data storage. Here we show the potential use of multifunctional sequence-defined macromolecules as a storage medium. As a proof-of-principle, we describe how short text fragments (human-readable data) and QR codes (machine-readable data) are encoded as a collection of oligomers and how the original data can be reconstructed. The amide-urethane containing oligomers are generated using an automated protecting-group free, two-step iterative protocol based on thiolactone chemistry. Tandem mass spectrometry techniques have been explored to provide detailed analysis of the oligomer sequences. We have developed the generic software tools Chemcoder for encoding/decoding binary data as a collection of multifunctional macromolecules and Chemreader for reconstructing oligomer sequences from mass spectra to automate the process of chemical writing and reading.

Multifunctional sequence-defined macromolecules for chemical data storage.

Eimeria bovis is an important coccidian parasite that causes high economic losses in the cattle industry. We recently showed that polymorphonuclear neutrophils (PMN) react upon E. bovis sporozoite exposure by neutrophil extracellular trap (NET) formation. We focused here on the molecular mechanisms that are involved in this process. The sporozoite encounter led to an enhanced surface expression of neutrophil CD11b suggesting a potential role of this receptor in E. bovis-mediated NETosis. Antibody-mediated blockage of CD11b confirmed this assumption and led to a significantly decreased sporozoite-triggered NET. In addition, E. bovis-induced NETosis was found to be Ca(2+)-dependent since the inhibition of store-operated calcium entry (SOCE) significantly diminished NET. Furthermore, NADPH oxidase, neutrophil elastase (NE) and myeloperoxidase (MPO) were confirmed as key molecules in sporozoite-triggered NETosis, as inhibition thereof blocked parasite-triggered NET. PMN degranulation analyses revealed a significant release of matrix metalloprotease-9 containing granules upon sporozoite exposure. We further show a significantly enhanced phosphorylation of ERK1/2 and p38 MAPK in sporozoite-exposed PMN indicating a key role of this signaling pathway in E. bovis-mediated NETosis. Accordingly, ERK 1/2 and p38 MAPK inhibition led to a significant decrease in NET formation. Finally, we demonstrate that sporozoite-induced NETosis is neither a stage-, species-, nor host-specific process.

Eimeria bovis-triggered neutrophil extracellular trap formation is CD11b-, ERK 1/2-, p38 MAP kinase- and SOCE-dependent.

Although alteration in host cellular translation machinery occurs in virus-infected cells, the role of such alteration and the precise pathogenic processes are not well understood. Influenza A virus (IAV) infection shuts off host cell gene expression at transcriptional and translational levels. Here, we found that the protein level of eukaryotic translation initiation factor 4B (eIF4B), an integral component of the translation initiation apparatus, was dramatically reduced in A549 cells as well as in the lung, spleen, and thymus of mice infected with IAV. The decrease in eIF4B level was attributed to lysosomal degradation of eIF4B, which was induced by viral NS1 protein. Silencing eIF4B expression in A549 cells significantly promoted IAV replication, and conversely, overexpression of eIF4B markedly inhibited the viral replication. Importantly, we observed that eIF4B knockdown transgenic mice were more susceptible to IAV infection, exhibiting faster weight loss, shorter survival time, and more-severe organ damage. Furthermore, we demonstrated that eIF4B regulated the expression of interferon-induced transmembrane protein 3 (IFITM3), a critical protein involved in immune defense against a variety of RNA viruses, including influenza virus. Taken together, our findings reveal that eIF4B plays an important role in host defense against IAV infection at least by regulating the expression of IFITM3, which restricts viral entry and thereby blocks early stages of viral production. These data also indicate that influenza virus has evolved a strategy to overcome host innate immunity by downregulating eIF4B protein. Influenza A virus (IAV) infection stimulates the host innate immune system, in part, by inducing interferons (IFNs). Secreted IFNs activate the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, leading to elevated transcription of a large group of IFN-stimulated genes that have antiviral function. To circumvent the host innate immune response, influenza virus has evolved multiple strategies for suppressing the production of IFNs. Here, we show that IAV infection induces lysosomal degradation of eIF4B protein; and eIF4B inhibits IAV replication by upregulating expression of interferon-induced transmembrane protein 3 (IFITM3), a key protein that protects the host from virus infection. Our finding illustrates a critical role of eIF4B in the host innate immune response and provides novel insights into the complex mechanisms by which influenza virus interacts with its host.

Influenza A virus-induced degradation of eukaryotic translation initiation factor 4B contributes to viral replication by suppressing IFITM3 protein expression.

Influenza virus neuraminidase (NA) is an interesting target of small-molecule antiviral drugs. We isolated a set of H5N1 NA-specific single-domain antibodies (N1-VHHm) and evaluated their in vitro and in vivo antiviral potential. Two of them inhibited the NA activity and in vitro replication of clade 1 and 2 H5N1 viruses. We then generated bivalent derivatives of N1-VHHm by two methods. First, we made N1-VHHb by genetically joining two N1-VHHm moieties with a flexible linker. Second, bivalent N1-VHH-Fc proteins were obtained by genetic fusion of the N1-VHHm moiety with the crystallizable region of mouse IgG2a (Fc). The in vitro antiviral potency against H5N1 of both bivalent N1-VHHb formats was 30- to 240-fold higher than that of their monovalent counterparts, with 50% inhibitory concentrations in the low nanomolar range. Moreover, single-dose prophylactic treatment with bivalent N1-VHHb or N1-VHH-Fc protected BALB/c mice against a lethal challenge with H5N1 virus, including an oseltamivir-resistant H5N1 variant. Surprisingly, an N1-VHH-Fc fusion without in vitro NA-inhibitory or antiviral activity also protected mice against an H5N1 challenge. Virus escape selection experiments indicated that one amino acid residue close to the catalytic site is required for N1-VHHm binding. We conclude that single-domain antibodies directed against influenza virus NA protect against H5N1 virus infection, and when engineered with a conventional Fc domain, they can do so in the absence of detectable NA-inhibitory activity. Highly pathogenic H5N1 viruses are a zoonotic threat. Outbreaks of avian influenza caused by these viruses occur in many parts of the world and are associated with tremendous economic loss, and these viruses can cause very severe disease in humans. In such cases, small-molecule inhibitors of the viral NA are among the few treatment options for patients. However, treatment with such drugs often results in the emergence of resistant viruses. Here we show that single-domain antibody fragments that are specific for NA can bind and inhibit H5N1 viruses in vitro and can protect laboratory mice against a challenge with an H5N1 virus, including an oseltamivir-resistant virus. In addition, plant-produced VHH fused to a conventional Fc domain can protect in vivo even in the absence of NA-inhibitory activity. Thus, NA of influenza virus can be effectively targeted by single-domain antibody fragments, which are amenable to further engineering.

Single-domain antibodies targeting neuraminidase protect against an H5N1 influenza virus challenge.

mAbs constitute an important biological tool for influenza virus haemagglutinin (HA) epitope mapping through the generation of escape mutants, which could provide insights into immune evasion mechanisms and may benefit the future development of vaccines. Several influenza A (H1N1) pandemic 2009 (pdm09) HA escape mutants have been recently described. However, the HA antigenic sites of the previous seasonal A/Brisbane/59/2007 (H1N1) (Bris07) virus remain poorly documented. Here, we produced mAbs against pdm09 and Bris07 HA proteins expressed in human HEK293 cells. Escape mutants were generated using mAbs that exhibited HA inhibition and neutralizing activities. The resulting epitope mapping of the pdm09 HA protein revealed 11 escape mutations including three that were previously described (G172E, N173D and K256E) and eight novel ones (T89R, F128L, G157E, K180E, A212E, R269K, N311T and G478E). Among the six HA mutations that were part of predicted antigenic sites (Ca1, Ca2, Cb, Sa or Sb), three (G172E, N173D and K180E) were within the Sa site. Eight escape mutations (H54N, N55D, N55K, L60H, N203D, A231T, V314I and K464E) were obtained for Bris07 HA, and all but one (N203D, Sb site) were outside the predicted antigenic sites. Our results suggest that the Sa antigenic site is immunodominant in pdm09 HA, whereas the N203D mutation (Sb site), present in three different Bris07 escape mutants, appears as the immunodominant epitope in that strain. The fact that some mutations were not part of predicted antigenic sites reinforces the necessity of further characterizing the HA of additional H1N1 strains.

Epitope mapping of the 2009 pandemic and the A/Brisbane/59/2007 seasonal (H1N1) influenza virus haemagglutinins using mAbs and escape mutants.

The BH3-only protein PUMA (p53-upregulated modulator of apoptosis) is a major regulator of apoptosis. It belongs to the Bcl-2 family of proteins responsible for maintaining mitochondrial outer membrane integrity by controlling the intrinsic (mitochondrial) apoptotic pathway. We describe here a new pathway regulating PUMA activation through the control of its subcellular distribution. Surprisingly, neither PUMA upregulation in normal activated human B lymphocytes nor high levels of PUMA in Burkitt's lymphoma (BL) were associated with cell death. We show that PUMA is localized to the cytosol in these cells. By contrast, various apoptosis-triggering signals were found to promote the translocation of PUMA to the mitochondria in these cells, leading to their death by apoptosis. This apoptosis was associated with the binding of mitochondrial PUMA to anti-apoptotic members of the Bcl-2 family, such as Bcl-2 and Mcl-1. This translocation was caspase-independent but was prevented by inhibiting or knocking down the expression of the MAPK kinase p38. Our data suggest that the accumulation of PUMA in the cytosol may be important for the participation of this protein in apoptosis without the need for prior transcription. This regulatory pathway may be an important feature of differentiation and tumorigenic processes.

Subcellular localization of PUMA regulates its pro-apoptotic activity in Burkitt's lymphoma B cells.

Atherosclerosis resulting from hyperlipidemia causes many serious cardiovascular diseases. To understand the systems changes associated with pathogenesis and progression of atherosclerosis, we comprehensively analyzed the dynamic metabonomic changes in multiple biological matrices of LDLR(-/-) mice using NMR and GC-FID/MS with gene expression, clinical chemistry, and histopathological data as well. We found that 12 week "Western-type" diet (WD) treatment caused obvious aortic lesions, macrophage infiltration, and collagen level elevation in LDLR(-/-) mice accompanied by up-regulation of inflammatory factors including aortic ICAM-1, MCP-1, iNOS, MMP2, and hepatic TNFα and IL-1β. The WD-induced atherosclerosis progression was accompanied by metabonomic changes in multiple matrices including biofluids (plasma, urine) and (liver, kidney, myocardial) tissues involving multiple metabolic pathways. These included disruption of cholesterol homeostasis, disturbance of biosynthesis of amino acids and proteins, altered gut microbiota functions together with metabolisms of vitamin-B3, choline, purines, and pyrimidines. WD treatment caused down-regulation of SCD1 and promoted oxidative stress reflected by urinary allantoin elevation and decreases in hepatic PUFA-to-MUFA ratio. When switching to normal diet, atherosclerotic LDLR(-/-) mice reprogrammed their metabolisms and reversed the atherosclerosis-associated metabonomic changes to a large extent, although aortic lesions, inflammation parameters, macrophage infiltration, and collagen content were only partially alleviated. We concluded that metabolisms of fatty acids and vitamin-B3 together with gut microbiota played crucially important roles in atherosclerosis development. These findings offered essential biochemistry details of the diet-induced atherosclerosis and demonstrated effectiveness of the integrated metabonomic analysis of multiple biological matrices for understanding the molecular aspects of cardiovascular diseases.

Metabonomic Changes Associated with Atherosclerosis Progression for LDLR(-/-) Mice.

The natural product montamine was originally assigned as a homodimer of moschamine linked by a N-N' bond at the serotonin side-chain. A total synthesis of the reported structure has shown this to be incorrect. Analysis of the spectroscopic data suggests that the dimerization site has been incorrectly assigned, and montamine is likely to be a 4,4'-bismoschamine natural product previously described in the literature.

Total synthesis of putative montamine and a proposed structural reassignment.

Important structural differences imply that human and mouse mast cell chymases may differ with respect to their enzymatic properties. We compared in this study the catalytic efficiencies of recombinant human chymase (rCMA1) and its functional murine homologue recombinant mouse mast cell protease-4 (rmMCP-4) toward a fluorogenic chymase substrate (Suc-Ala-Ala-Pro-Phe-7-amino-4-methylcoumarin (AMC) and by their ability to convert Big-endothelin (ET)-1 into ET-1 (1-31) using a LC/MS/MS system. Activities toward a fluorogenic substrate (Suc-Leu-Leu-Val-Tyr-AMC) and Big ET-1 were also measured in extracts from mouse peritoneal mast cells, LUVA human mast cell-like cells and human aortas. The specificity of these activities was assessed with the chymase inhibitor TY-51469 (2-[4-(5-fluoro-3-methylbenzo[b]thiophen-2-yl)sulfonamido-3-methanesulfonyl-phenyl]thiazole-4-carboxylic acid). For similar affinities, rmMCP-4 showed a higher activity toward the fluorogenic substrate and a higher ability to process Big ET-1 as compared to recombinant CMA1 (chymase activity (kcat/KM in μM(-1)s(-1)): 2.29 × 10(-4)vs. 6.41 × 10(-6); ET-1 (1-31) production: 2.19 × 10(-3)vs. 6.57 × 10(-5)), and both of these activities of mouse and human chymase were sensitive to TY-51469. Furthermore, extracts from mouse peritoneal mast cells, LUVA cells and human aorta homogenates contained processing activities toward the fluorogenic chymase substrate as well as Big ET-1, all of which were sensitive to TY-51469. Finally, the pressor responses to Big ET-1 but not to ET-1 were significantly reduced in conscious and free moving mMCP-4 KO mice when compared to wild type congeners. Our results suggest that both mouse and human chymases have potent ET-1 (1-31)-producing abilities, with the murine isoform being more efficient.

Chymase inhibitor-sensitive synthesis of endothelin-1 (1-31) by recombinant mouse mast cell protease 4 and human chymase.

Tetraalkylammonium hydroxides have been found to mediate regioselective deacylation of cellulose esters. This deacylation surprisingly shows substantial selectivity for the removal of the acyl groups at O-2/3, affording cellulose-6-O-esters by a simple, efficient one-step process. The mechanism for this deacylation was investigated by studying the effect of tetraalkylammonium cation size upon ester deacylation selectivity. We hypothesize that coordination of the tetraalkylammonium cation by the ester oxygen atoms of the vicinal 2,3-acetate groups may drive the unexpected regioselectivity at the secondary alcohol esters. Broad scope with respect to ester type was demonstrated; regioselective O-2,3 deacylation was observed with cellulose acetate, propionate, butyrate, hexanoate and benzoate triesters. The scope of this deacylation of cellulose acetates has been investigated to understand how to carry it out most efficiently. Reaction with TBAOH in pyridine was the most effective process, providing the highest selectivity.

乙酰氯溶液

1 M in methylene chloride

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