Extended applications of electric cell-substrate impedance sensing for assessment of the structure-function of α2β1 integrin

Electric cell-substrate impedance sensing (ECIS) was applied to assess the structure-function of α2β1 integrin, receptor for collagen and laminin. On collagen-coated gold electrodes, expression of this integrin on human rhabdomyosarcoma (RD) cells (RDX2C2) yielded a five-fold increase in resistance when compared with mock transfected RD (RDpF) cells (34.5±5.2 versus 6.5±0.8 Ω/cell). An intermediate level of 16±2 Ω/cell was measured upon expression of an α2β1 mutant that lacked the α2 cytoplasmic domain (RDX2CO). On laminin, the resistance measured for RDX2C2 cells was also higher but only twice that of RDpF cells at 71±4 and 37±4 Ω/cell, respectively. In comparison, RDX2CO cells (38±4 Ω/cell), exhibiting no enhanced adhesive function, yielded a similar result to that of RDpF cells. On fibronectin, RDX2C2 and RDpF cells, exhibiting comparable levels of adhesion, were similar in resistance measurements at 85±5and 89±7 Ω/cell, respectively. It has been shown that deletion of α2 cytoplasmic domain results in dysregulated recruitment of the α2β1 mutant to focal adhesion complexes that mediate binding of fibronectin. RDX2CO cells on fibronectin, exhibiting reduced adhesive function, was associated with noticeably lower resistance (60±4 Ω/cell). Monitoring electroporation of the RD plasma membrane also indirectly validated cell attachment as reflected by the resistance measured. Results from this study demonstrated the potential of ECIS for study of the structure-function of βl integrin adhesion receptors.     

烷基化螺吡喃吲哚的合成及光学性质研究

为了增加螺吡喃吲哚与透明聚合物（ＰＭＭＡ）的相溶性,在螺吡喃吲哚分子中引入长烷基链,合成了１′－「十八烷基」－３′,３′－二甲基－６－硝基－８－「二十二酰氧基」－螺「２Ｈ－１－苯并吡喃－２,２′－二氢吲哚」,并用ＮＭＲ确定各中间体和最终产物的结构,ＨＰＬＣ显示产物中烷基化螺吡喃吲哚含量在９７％以上。将烷基化螺吡喃吲哚与ＰＭＭＡ制成厚度为５００ｎｍ左右的膜,研究该膜对紫外光的响应,获得烷基化螺吡喃吲哚开环和紫外吸收的关系,以及Ｊ－耦合构型与陈化的关系。     

环氧烷化合物在有机合成中的应用

综述了近年来环氧烷化合物在有机合成中的应用。环氧烷化合物的开环反应可以用来合成其它方法难以合成的多官能团化合物，或通过开环和修饰合成其他环状化合物。另外，利用该反应还可以提供保护基以及立体、区域选择性地合成各种有机化合物。参考文献23篇。     

Alternative paths in the ring opening of oxadiaziridine: The diimide N-oxide versus the oxodiimide rearrangement

The ring opening of the oxadiaziridine by cleavage of the N-N bond has been theoretically investigated by SCF calculations improved with limited CI. The possible competition of this reaction with the better known ones (N-O bond cleavage, inversion of the N atom) is discussed. The chemical implications of the formation of a new type of 1,3-dipole are examined.     

Macrocycle opening in crown ethers

Macrocycle opening in derivatives of benzocrown ethers under the action of amines is affected by the nature of the heteroatoms in the macrocycle, the nature of the functional group in the benzene ring of the crown ether, and the length, branching, and number of hydrocarbon radicals at the amine nitrogen atom. A distinguishing feature of this reaction is the template effect of MeNH₃ ⁺, Me₂NH₂ ⁺, Na⁺, and K⁺ ions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 687–692, March, 1996.For Part I see Ref. 1.     

Macrocycle opening in formyl derivatives of benzocrown ethers under the action of methylamine

A new method for synthesizing nitrogen-containing podands by nucleophilic regioselective cleavage of the macrocycle in formyl derivatives of benzocrown ethers by heating with methylamine and methylammonium chloride has been developed. This reaction is the first example of crown ether opening by a nitrogen-containing nucleophile.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 950–953, May, 1995.     

Influence of mechanical properties of pectin films on charge density and charge density distribution in pectin macromolecule

The hydration and mechanical properties of citrus pectin films were examined in conditions relevant to those in the plant cell wall. The pectins used for this study varied in the degree of esterification (DE) (high or low) and charge distribution on the backbone (random or block). The hydration of the films was controlled in an osmotic pressure experiment using polyethylene glycol solutions (PEG 20000). Hysteresis tests at constant deformation rate (stress vs deformation) were used for investigating the mechanical behaviour of films. Mechanical and hydration properties of pectin films were examined as a function of charge density, charge density distribution and counterion environment—K⁺, Ca²⁺, Mg²⁺. Swelling decreased with increasing counterion concentration. The effect is stronger in the case of Ca²⁺ and Mg²⁺ for low esterified pectins and therefore crosslinks from divalent ions could be assumed. The crosslink effect is confirmed in mechanical experiments where an increase in the film tensile modulus is observed with increasing counterion concentration. It is shown for the first time that in case of highly concentrated pectin solutions Mg²⁺ cations also act as a crosslinker for pectin macromolecules.     

On the Rigidity of Polynorbornenes with Dipolar Pendant Groups

A range of polynorbornenes (PNBs) with fused dipolar pendant groups at C‐5,6 positions was synthesized by ring‐opening metathesis polymerization catalyzed by a ruthenium carbene complex (Grubbs I). Photophysical studies, EFISH measurements, and atomic force microscopy images have been used to investigate the structures and morphology of these polymers. These results suggest that the polymers may adopt rigid rod‐like structures. The presence of the double bonds in PNBs appeared to be indispensable for the rigidity of the polymers. Interaction between unsaturated pendant groups may result in coherent alignment leading to a rod‐like structure.     

环状碳酸酯低聚物的合成及其开环聚合的研究

环状碳酸酯低聚物的合成及其开环聚合的研究陈雨萍魏玮李革（中国科学院化学研究所工程塑料国家重点实验室北京１０００８０）关键词环状碳酸酯低聚物，聚碳酸酯，开环聚合环状单体的开环聚合在合成高聚物方面具有突出的优点，即在聚合过程中没有副产物、热效应低、聚合...     

Synthesis,Structure, and Fluxionality of Strained Hypercoordinate Silicon‐Bridged [1]Ferrocenophanes

The first hypercoordinate sila[1]ferrocenophanes [fcSiMe(2‐C₆H₄CH₂NMe₂)] ( 5 a ) and [fcSi(CH₂Cl)(2‐C₆H₄CH₂NMe₂)] ( 5 b ) (fc=(η⁵‐C₅H₄)Fe(η⁵‐C₅H₄)) were synthesized by low‐temperature (?78 °C) reactions of Li[2‐C₆H₄CH₂NMe₂] with the appropriate chlorinated sila[1]ferrocenophanes ([fcSiMeCl] ( 1 a ) and [fcSi(CH₂Cl)Cl] ( 1 d ), respectively). Single‐crystal Xray diffraction studies revealed pseudo‐trigonal bipyramidal structures for both 5 a and 5 b , with one of the shortest reported Si???N distances for an sp³‐hybridized nitrogen atom interacting with a tetraorganosilane detected for 5 a (2.776(2) Å). Elongated Si? C_ipso bonds trans to the donating NMe₂ arms (1.919(2) and 1.909(2) Å for 5 a and 5 b , respectively) were observed relative to both the non‐trans bonds ( 5 a : 1.891(2); 5 b : 1.879(2) Å) and the Si? C_ipso bonds of the non‐hypercoordinate analogues ([fcSiMePh] ( 1 b ): 1.879(4), 1.880(4) Å; [fcSi(CH₂Cl)Ph] ( 1 e ): 1.881(2), 1.884(2)). Solution‐state fluxionality of 5 a and 5 b , suggestive of reversible coordination of the NMe₂ group to silicon, was demonstrated by means of variable‐temperature NMR studies. The ΔG^≠ of the fluxional processes for 5 a and 5 b in CD₂Cl₂ were estimated to be 35.0 and 37.6 kJ mol^?1, respectively (35.8 and 38.3 kJ mol^?1 in [D₈]toluene). The quaternization of 5 a and 5 b by MeOTf, to give [fcSiMe(2‐C₆H₄CH₂NMe₃)][OTf] ( 7 a‐ OTf) and [fcSi(CH₂Cl)(2‐C₆H₄CH₂NMe₃)][OTf] ( 7 b‐ OTf), respectively, supported the reversibility of NMe₂ coordination at the silicon center as the source of fluxionality for 5 a and 5 b . Surprisingly, low room‐temperature stability was detected for 5 b due to its tendency to intramolecularly cyclize and form the spirocyclic [fcSi(cyclo‐CH₂NMe₂CH₂C₆H₄)]Cl ( 9 ‐Cl). This process was observed in both solution and the solid state, and isolation and Xray characterization of 9 ‐Cl was achieved. The model compound, [Fc₂Si(2‐C₆H₄CH₂NMe₂)₂] ( 8 ), synthesized through reaction of [Fc₂SiCl₂] with two equivalents of Li[2‐C₆H₄CH₂NMe₂] at ?78 °C, showed a lack of hypercoordination in both the solid state and in solution (down to ?80 °C). This suggests that either the reduced steric hindrance around Si or the unique electronics of the strained sila[1]ferrocenophanes is necessary for hypercoordination to occur.