Impairing effect of fibrinogen on the mono-/bi-layer form of bovine lung surfactant

Lung surfactant (LS), a lipid–protein mixture responsible for alveolar stability, is inhibited by serum proteins leaked into the lungs in disease. Interaction of bovine lipid extract surfactant (BLES), a clinical replacement lung surfactant, with serum protein fibrinogen (Fbg) was studied employing various structural and biophysical techniques in adsorbed films and bulk bilayer dispersions. Surface tension area isotherms of the adsorbed films revealed the suppression of interfacial activity of BLES by Fbg (adsorption and surface tension reduction). Fbg, predominantly associated with the fluid phase of BLES films, resulted in the aggregation of the gel lipid domains as evidenced by atomic force microscopy. BLES bilayer dispersion showed phase transition from a diffused gel to liquid–crystalline phase in the temperature range 10–35 °C as studied by differential scanning calorimetry (DSC). Fbg resulted in the shift of peak to a higher transition temperature for the maximal heat flow (T _max) of BLES dispersions. Combined Raman and FTIR spectral studies of the BLES/Fbg dispersions revealed that Fbg altered the –CH₂–, –CH₃, and –PO₄ ^? vibrational modes of the phospholipids present in BLES, suggesting the condensing and dehydrating effect of the protein on surfactant. Studies suggest that Fbg, by directly interacting with the gel lipids in LS in bulk dispersions, alter the packing of the films formed at the interface, and can be used as a specific model for lung disease.     

A rapid method for simultaneous determination of 52 marker compounds in Xiao‐Qing‐Long‐Tang by ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry†

Xiao‐Qing‐Long‐Tang (XQLT) is a classical Chinese medicine formula. It is generally used for the treatment of common cold, bronchial asthma, and allergic rhinitis in Asia. In this study, a multicomponent quantification fingerprinting approach based on ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry has been developed for the analysis of compounds in XQLT in 14.5 min. A total of 52 compounds were identified by co‐chromatography of sample extract with authentic standards and comparing the retention time, UV spectra, molecular ions and characteristic fragment ions with those of authentic standards, or tentatively identified by MS^E determination along with Mass Fragment software. Moreover, the method was validated for the simultaneous quantification of 16 components in XQLT commercial products. The method is practical for comprehensive standardization of XQLT and holistic comparison of its commercial products from different manufacturers.     

Extremal Betti numbers of edge ideals

Archiv der Mathematik - Let A be an algebra over a field F of characteristic zero. For every $$n\ge 1$$ , let $$\delta _n(A)$$ be the number of linearly independent multilinear proper central...     

Total dual integrality of the linear complementarity problem

Annals of Operations Research - In this paper, we introduce total dual integrality of the linear complementarity problem (LCP) by analogy with the linear programming problem. The main idea of...     

Syntheses of the First Se-Nitrososelenol and Related Compounds

Abstract

The first stable Se-nitrososelenol (RSeNO) and selenonitrate (RSeNO₂) were synthesized by taking advantage of bowl-type steric protection groups, and their spectral properties and reactivities were elucidated. X-ray crystallographic analysis established their structures.     

Synthesis of Linear Poly(1-Benzyltrimethyleneimine) by the Hofmann Reaction of Poly(1-Cyanoethyltrimethyleneimine) Quaternized with Benzylbromide

The synthesis of a linear polymer having a tertiary amino group in a part of the main chain has been attempted by several methods. However, it was difficult for the linear polyamine to form because of the complicated reaction of the amino group. In the polymerization of weakly basic cyclic amines, e.g., 1-cyanoethylazetidine or 1-cyanoethylaziridine, high molecular weight polymers, poly-1-cyanoethyltrimethyleneimine (poly-CET) and poly-1-cyanoethyl-ethyleneimine (poly-CEE), were obtained. An attempt was made to convert poly-CET and poly-CEE into poly(l-benzylalkyleneimine)s (poly-BET and poly-BEE). Linear poly-BET was prepared by the alkylation of poly-CET (MW about 6000) with benzylbromide, followed by the elimination of the cyanoethyl group of polymer by heating. The poly-BET obtained was a white, greasy substance with a molecular weight of about 5000; its structure was determined by NMR spectroscopy. The cyanoethyl groups were replaced completely by benzyl groups. However, poly-BEE with a complete exchange to benzyl group was not obtained from poly-CEE due to the remaining cyanoethyl groups. Residual cyanoethyl groups replaced about 40% of the amino groups in poly-CEE.     

Polymerization Mechanism of Vinyl Chloride with Trialkylaluminum-Lewis Base Catalyst and Thermal Stability of Poly(vinyl Chloride)

The mechanism of vinyl chloride polymerization by the tri-ethylaluminum-Lewis base-carbon tetrachloride catalyst system and the thermal stability of the resulting polymer were investigated. When the Lewis base is multidentate, the resultant complex with triethylaluminum shows significantly high catalytic activity for radical polymerization of vinyl chloride in the presence of carbon tetrachloride to give a white powder with high molecular weight. Carbon tetrachloride accelerates the rate of polymerization and participates in an initiating process rather than in a propagating step. The thermal stability of the polymer prepared with this catalyst system is much superior to that of commercial polyvinyl chloride), although the numbers of the double bonds in a chain end and of the head-to-head linkage are similar in both samples, suggesting that the thermally unstable structures of the former react with triethylaluminum to give the thermally stable structure on the polymerization process.     

Metal-Containing Initiator Systems. 30. Vinyl Polymerization Initiated with Bis(ethyl acetoacetato)copper(II) and Maleimide

Some electron-accepting compounds such as maleimide (MIm), maleic anhydride (MAn), and tetracyanoquinodimethane were found to show pronounced accelerating effects on vinyl polymerization initiated with metal chelates. The polymerization of methyl methacrylate (MMA) initiated with bis(ethyl acetoacetato)-copper(II) (Cu(eacac)₂) and MIm was studied kinetically in benzene. The overall activation energy of the polymerization was calculated to be 11.5 kcal/mol. This value was much lower than that (17.6 kcal/mol) for the polymerization of MMA with Cu(eacac)₂ alone. The polymerization rate (R_p) was expressed as R_p =k[MIm]^1/2 [Cu(eacac)₂]^1/2 [MMA] The first-order dependence of R_p on the monomer concentration indicated that the monomer had no participation in the initiation step, in contrast with polymerization in the absence of MIm (where a monomer concentration dependence of 1.4th order was observed). Electronic spectroscopic study revealed that a complex between MIm and Cu(eacac)₂ had been formed. The ligand radical, an acetylcarboethoxymethyl radical, was trapped by 2-methyl-2-nitrosopropane in the reactions of Cu(eacac)₂ with MIm and with MAn in benzene. From these results the mechanism of the initiation of polymerization is discussed.