Synthesis of a polyvinyl-polyamino acid graft copolymer

A copolymer having reactive primary amino groups was synthesized by the copolymerization of styrene and N-methyl-N-(4-vinylphenethyl)ethylenediamine ( 1 ). Polymerization of N-carboxy amino acid anhydrides (NCA's) of L -alanine, γ-benzyl-L -glutamate, or β-benzyl-L -aspartate was initiated by the primary amino groups of this copolymer to give a novel polyvinyl-polyamino acid graft copolymer.     

Copolymerization of γ-butyrolactone and β-butyrolactone

The copolymerization of a 4-membered β-butyrolactone (βBL) and a thermodynamically stable 5-membered γ-butyrolactone (γBL) proceeds in the bulk state with BF₃ · OEt₂ as a catalyst at room temperature to give poly[(3-hydroxybutyrate)-co-(4-hydroxybutyrate)] (P(3HB-co-4HB)) whose structure is identical with that of a polyester formed by microorganisms. The copolymer structure was confirmed by ¹H and ¹³C NMR spectroscopy. The monomer reactivity ratios were r_(γBL) = 0.48 and r_(βBL) = 0.58, respectively, and the unit composition of 4HB increases to 56% at high γBL to βBL ratio in the feed. End group analysis of the copolymer suggests the presence of a hydroxyl group and a carboxyl group at the ends of each polymer molecule. It was postulated that the monomers activated by BF₃ react with the hydroxy group derived from the water contaminant in the monomers.     

Cationic copolymerization of cyclic ethers with vinyl compounds. IV. Cationic copolymerization of propylene oxide with styrene

When a mixture of propylene oxide and styrene in methylene dichloride was reacted with boron trifluoride etherate as catalyst, a copolymer and the homopolymer of propylene oxide were formed. The poly(propylene oxide) was formed almost quantitatively in the initial stage of the reaction. The amount of homopolymer then gradually decreased as the formation of the copolymer progressed. The copolymer was also formed by the polymerization of styrene in the presence of poly(propylene oxide). The copolymerization is thought to proceed largely by a chain-transfer reaction.     

Crystallization of polypeptides in the course of polymerization, 7. Crystallization of poly(γ-methyl-L-glutamate), poly(γ-benzyl-L-glutamate) and poly(β-benzyl-L-aspartate)

Heterogeneous polymerizations of γ-methyl-L -glutamate N-carboxy anhydride (NCA), γ-benzyl-L -glutmate NCA, and β-benzyl-L -aspartate NCA were carried out using butylamine as initiator in acetonitrile at 30°C. The oligomer chains formed in the beginning of the polymerization crystallized into the antiparallel β-form and thereafter the α-helical chains grew from the active sites of the β-chains. The polymerization of γ-methyl-L -gultamate NCA proceeded to 100% conversion and accordingly gave rise to high molecular weight poly(γ-methyl-L -glutamate). The polymerizations of γ-benzyl-L -glutamate NCA and β-benzyl-L -aspartate NCA stopped at 54% and 16%, resp. The levelling-off of the conversion at such low values, in spite of the α-helical chain growth, may be due to the occlusion of the active chain ends of the resultant poly(γ-benzyl-L -glutamate) and poly(β-benzyl-L -aspartate) into the crystals. It was concluded that the interlamellar crystallization was induced by the intermolecular interaction between the benzyl groups of the polymer side chains, giving rise to the occlusion of the active growing chain ends into the interstices of the crystal formed during the polymerization.     

Cationic copolymerisation of 1,3-dioxolane with 5-methyl-2,3-dihydro-2-furanone initiated with triethyloxonium tetrafluoroborate

The copolymerization of 1,3-dioxolane ( 1 ) with 5-methyl-2,3-dihydro-2-furanone ( 2 ) which has two functional groups, a CC double bond and a γ-lactone ring, was carried out in nitrobenzene, dichloromethane, and toluene at 0 C with triethyloxonium tetrafluoroborate as initiator. NMR analysis of the microstructure of the copolymer disclosed that a random copolymer was formed in this system, and that the exclusive addition of the growing chain end of 1 to the CC double bond occurred in the cross-propagation from 1 to 2 . The highly selective reactivity of the growing species of 1 was discussed. Homopolymerizability of 2 was also studied by using various cationic and radical initiators.     

流动相对西罗莫司异构体在反相液相色谱上分离效果影响的研究

研究不同流动相对西罗莫司异构体在反相液相色谱上分离效果的影响,为准确测定西罗莫司的含量提供依据。色谱柱采用YMC J’sphere ODS-H80,流动相分别采用不同体积比例的水/乙腈(40/60,35/65,30/70,v/v)或水/甲醇(20/80,15/85,10/90,v/v)。结果表明:以水/乙腈或水/甲醇二元溶剂为流动相时,随着有机溶剂比例的增加,西罗莫司异构体(β峰与γ峰)的保留时间都变短,峰宽都变狭窄,分离度也相应降低。选择流动相水/乙腈(35/65)或水/甲醇(15/85),西罗莫司的异构体(β峰与γ峰)均能完全分离。与流动相水/乙腈(35/65)相比,以水/甲醇(15/85)作流动相,西罗莫司β异构体色谱峰的保留时间更短,峰宽更狭窄,是水/甲醇与水/乙腈流动相体系中的最佳条件。     

Interferon induced in human leukocytes by mitogens: production,partial purification and characterization

Interferon was induced in leukocyte suspensions from human buffy coats by exposure to phytohemagglutinin P, concanavalin A (Con A) and staphylococcal enterotoxin A, under a variety of cell culture conditions. Con A was found to rapidly (within 12 h) induce high yields of antiviral activity (1.5 units/1000 cells). Lesser yields were obtained with the other two mitogens studied. The interferon was partially purified to a spec. act. around 10^5.3 units/mg protein, by batch adsorption on controlled-pore glass (CPG) beads and desorption by ethylene glycol. This material was characterized as containing mainly γ-type interferon. Specifically on gel filtration, a fraction of 45 000 daltons was obtained which could account for virtually all antiviral activity present in the starting material. Furthermore, the ethylene glycol-eluted antiviral activity was acid-labile, serologically distinct from a and β-type interferon and strictly species-specific (no activity detectable on any of the available cell species sensitive to α and β-type interferon). The crude culture supernatant also contained some antiviral activity which resembled β-type interferon in that it adsorbed to CPG, could be desorbed by pH 2 buffer, was acid-resistant and could be neutralized by a specific anti-fibroblast interferon antiserum. The CPG/ethylene glycol-purified γ-type interferon preparation was found to inhibit the growth of certain lymphoblastoid cells (Daudi and Molt-4). It also potentiated natural killer activity of fresh donor lymphocytes. In both respects, the γ-type interferon preparation was not significantly more active than preparations of a and β-interferon of similar antiviral potency.     

Studies of in situ-forming hydrogels by blending PLA-PEG-PLA copolymer with silk fibroin solution

Hydrogels had been prepared by blending PLA-PEG-PLA copolymer with Bombyx mori silk fibroin (SF) solution. Copolymers were synthesized by ring opening polymerization of L-lactide in the presence of dihydroxyl PEG with molar mass of 400 and 1000, and characterized by using (1)H NMR and DSC. Hydrogels formed leaf-like lamellar structures with many nanoglobules which may reserve drugs or growth factors more effectively. Rheological measurements indicated that the adding of copolymer significantly accelerated the hydrogelation of silk fibroin solution which leads to orders-of-magnitude increase in the complex shear modulus to form rigid hydrogel. Hydrogelation kinetics could be controlled easily by changing the concentration ratio, kinds of copolymer and hydrogelation temperature, suggesting the hydrogels could be formed in situ under physiological conditions with suitable mechanical properties. Furthermore, Fourier transform infrared, X-ray diffraction, and differential thermal analysis were employed to study the structure of hydrogels. The copolymer and SF in blend hydrogels were phase separation. There was an increase of β-sheet content and formation of silk II structure during hydrogelation. These results may indicate that copolymer/SF hydrogels could be a valuable candidate scaffold as in situ-forming hydrogels for drug/growth factor release in tissue engineering.     

In Vitro Production of an Amyloid-Like Substance from γ3 Heavy Chain Disease Protein

Zu protein, a γ₃-heavy chain disease protein isolated from the urine of a patient with γ-heavy chain disease and amyloidosis, was digested with pepsin in pH 3.5 buffer at 37d`C. The precipitate which formed was Congo red positive and exhibited green birefringence in polarized light. Electron microscopy, by negative staining, revealed fibrils with dimensions 70-80 Å x 850 - 1950 Å. These findings were consistent with those obtained from amyloid fibrils derived from pepsin digestion of certain Bence Jones proteins. The X-ray diffraction pattern of the dried precipitate yielded two rings. The outer ring corresponded to a spacing of approximately 4.7 Å, and the inner ring corresponded to a spacing of approximately 10.6 Å. These dimensions are consistent with β-pleated sheet structure. The mildly reduced and alkylated Zu precipitate demonstrated an approximate molecular weight of 8000 daltons on SDS polyacrylamide gel electrophoresis. Automatic amino-terminal sequence analyses of the mildly reduced and alkylated Zu precipitate suggested that the polypeptide chain was blocked. It seems reasonable to assume that Zu γ₃-heavy chain disease protein was related to the widespread amyloidosis found in this patient.     

FTIR spectroscopic studies of interfacial reactions between amino functionalized silicon surfaces and molten maleic anhydride copolymers

The interactions of two reactive maleic anhydride copolymers, a styrene maleic anhydride copolymer and an alternating copolymer of malic anhydride and α-olefin side chains, with amino-functionalized surfaces were studied by means of FTIR-ATR spectroscopy. The interfacial processes were detected at a planar surface of a thermally oxidized silicon as internal reflecting element. This ATR element can be understood as a model for a glass fiber which is used as reinforcing material in polymer matrices. A typical glass fiber coupling agent, γ-aminopropyltriethoxysilane (γ-APS), was used to functionalize the silicon dioxide layer. It was found that the amino groups of the amino siloxane network layer, which were obtained by a coating procedure with γ-APS, react with the anhydride groups of the copolymer melt to form amic acid structures and imide structures depending on the chemical composition of the copolymers and the temperature.     

Crystallization of the γ-form of isotactic poly(propylene)

The pure γ-form of isotactic poly(propylene) can be obtained by melt-crystallization starting from a fraction of a random ethylene-propene copolymer (ethylene content 4 wt.-%) soluble in p-xylene at 28°C. Some structural models previously reported are tested by comparing calculated wide-angle X-ray diffraction patterns with the experimental ones. A method for the quantitative determination of the γ-form crystallinity by X-ray line profiles is proposed. The original copolymer and its fractions are characterized by differential scanning calorimetry and ¹³C NMR techniques.     

Association of three-block copolymers polycaprolactam-block-polystyrene-block-polycaprolactam

Colloidal particles of three-block copolymers polycaprolactam-block-polystyrene-block-polycaprolactam, formed in a solvent mixture toluene/2,2,3,3-tetrafluoropropanol as a good solvent of polycaprolactam, were studied by static and dynamic light scattering and transmission electron microscopy. Two kinds of spherical multimolecular particles differing in size were found in the solution. The smaller particles containing tens of copolymer molecules were interpreted as regular copolymer micelles, and the larger particles formed from thousands of copolymer molecules were interpreted as associates of these micelles.     

Characterization of ethylene-propene copolymers prepared with heterogeneous titanium-based catalysts

Ethylene-propene (EP) copolymers prepared with various heterogeneous titanium-based Ziegler-Natta catalysts, i. e., δ-TiCl₃, β-TiCl₃, and MgCl₂-supported titanium catalysts were fractionated by successive solvent extraction. Wide composition distributions were observed for all samples. Composition distributions of some samples were investigated precisely by temperature-programmed elution column fractionation. The fractionation data showed that these copolymers are a mixture of polyethylene and of copolymers with different structures, i. e., random and block copolymers. In every sample random copolymers were found most abundantly, the propylene sequences being present only as mmmm pentads. These data suggest that random copolymer is formed on an isospecific site.     

Structure-property relationships of meta-kerateine biomaterials derived from human hair

The structure-property relationships of kerateine materials were studied by separating crude hair extracts into two protein sub-fractions, referred to as α- and γ-kerateines, followed by their de novo recombination into meta-kerateine hydrogels, sponges and films. The kerateine fractions were characterized using electrophoresis and mass spectrometry, which revealed that the α-fraction contained complexes of type I and type II keratins and that the γ-fraction was primarily protein fragments of the α-fraction along with three proteins of the KAP-1 family. Meta-kerateine materials with increased amounts of γ-kerateines showed diminished physical, mechanical and biological characteristics. Most notably, materials with higher γ-content formed less elastic and less solid-like hydrogels and sponges that were less hydrolytically stable. In addition, a model biological assay showed that meta-kerateine films with greater amounts of γ-kerateines were less supportive of hepatocyte attachment. Investigation into the mechanism of attachment revealed that hepatocyte adhesion to meta-kerateines is not mediated by the β1 integrin subunit, despite the presence of LDV binding motifs within the type I α-keratins. This work to define the role of protein composition on biomaterial function is essential for the optimization of keratin biomaterials for biomedical applications.     

On the copolymerization of trioxane with acenaphthylene

With the aim of preparing copolymers of trioxane with acenaphthylene, the polymerization of a mixture of both monomers was carried out in the presence of boron trifluoridediethyl etherate in benzene and tetrachloromethane and in melt. In most monomer ratios, irrespective of the degree of conversion, products were obtained, which were composed of two fractions: one fusible and soluble in benzene and tetrachloromethane, containing almost pure polyacenaphthylene, and another infusible and insoluble in organic solvents with a high polyformaldehyde content. On polymerization of the monomer mixture under the action of γ-rays only insoluble and infusible products were formed. On the basis of the experimental results and the literature data an attempt is made to explain the formation of insoluble products and an opinion is expressed, that no copolymerization of the monomers is likely to take place under the experimental conditions employed.     

Influence de la solvatation préférentielle dans les réactions de greffage. Polydispersité en composition des copolymères SAN dans les résines ABS

ABS resins formed by copolymerization of styrene (S) and acrylonitrile (AN) in the presence of polybutadiene, consist of a mixture of SAN graft copolymer on polybutadiene and of ungrafted SAN copolymer. After separation and analysis, the AN contents of the grafted and ungrafted SAN are compared. The change of the AN contents as a function of the conversion and the concentration of polybutadiene is studied. As a consequence of the preferential solvation of polybutadiene by styrene and the initiator, the grafted SAN has a lower AN content than the non grafted SAN. At low conversions, where preferential solvation is maximum, it is also possible to show the presence of non grafted SAN which is formed in the polybutadiene coil or polybutadiene medium (“internal free SAN”). The characteristics of this “internal free SAN” are similar to those of the grafted SAN and especially its AN content is lower than that of SAN copolymer prepared under azeotropic conditions in the absence of polybutadiene.     

Surface characterizations of copolymer films with pendant monosaccharides

We copolymerized a monomer with a pendant glucose unit (GEMA) with methyl methacrylate (MMA) and prepared copolymer films with pendant monosaccharides by casting the copolymer solution on glass plates. The surfaces of the copolymer films were characterized by contact angle measurements, X-ray photoelectron spectroscopy (XPS) and protein adsorption measurements, and compared with the surface of 2-hydroxyethyl methacrylate (HEMA)-MMA copolymer films. The surface free energy of the GEMA-MMA and HEMA-MMA copolymer was calculated from the contact angle of methylene diiodide and glycerol on the copolymer films. The surface free energy of the films increased gradually with increasing GEMA or HEMA content. The surface free energy of GEMA-MMA copolymers was larger than that of HEMA-MMA copolymers in the whole range of composition. The results of XPS measurements suggest that the fraction of GEMA at the copolymer surface increases as the content of GEMA in the copolymer increases. This indicates that introduction of GEMA makes the copolymer surface more hydrophilic. Further more, the higher the GEMA content is, the smaller amounts of fibrinogen and γ-globulin are adsorbed at the copolymer surface. The copolymer with a GEMA content of 20 mol-% hardly adsorbs fibrinogen and γ-globulin at all.     

遗传性白内障小鼠晶状体的比较蛋白质组分析

目的： 比较研究先天性遗传性白内障的晶状体蛋白质表达谱的改变。方法: 采用自发的Crygs基因突变先天性隐性遗传白内障小鼠模型,分别提取白内障与正常小鼠晶状体总蛋白,进行固相pH梯度（IPG）等电聚焦双向电泳,R－250染色,使用PDQuest 7.30图像分析软件分析电泳图像。选择部分差异蛋白点胶上酶解,应用MALDI-TOF/TOF仪器进行串联质谱（MS/MS）鉴定及分析。结果: 上样量为882 μg时,白内障和正常小鼠分别检测到(417±53)个蛋白点（n=3）和(370±41)个蛋白点（n=3）。上样量为190 μg时,白内障和正常小鼠分别检测到(60±7)个蛋白点和(57±5)个蛋白点（n=3）。对γS、BFSP/filensin、γF、βA1、βB1、βB2和αB等7种差异蛋白进行了鉴定。突变小鼠晶状体正常γS、念珠状纤维结构蛋白（BFSP/filensin）缺失,γF表达下调（＜4倍）,异常βA1、βB1、βB2和αB表达上调（＞4倍）,分子量比正常小,提示βA1、βB1、βB2和αB可能发生裂解。结论: 蛋白质的双向电泳和质谱分析有助于基因突变后下游蛋白的功能分析。Crygs基因突变导致γS晶状体蛋白的异常,并引起细胞骨架蛋白（BFSP/filensin）和其它晶状体蛋白（γF、βA1、βB1、βB2和αB等）继发改变,从而间接诱发白内障。     

Sendai virus induced cytoplasmic actin remodeling correlates with efficient virus particle production

Cytoplasmic actins have been found interacting with viral proteins and identified in virus particles. We analyzed by confocal microscopy the cytoplasmic β- and γ-actin patterns during the course of Sendai virus infections in polarized cells. We observed a spectacular remodeling of the β-cytoplasmic actin which correlated with productive viral multiplication. Conversely, suppression of M during the course of a productive infection resulted in the decrease of particle production and the absence of β-actin remodeling. As concomitant suppression of β- and γ-actins resulted as well in reduction of virus particle production, we propose that Sendai virus specifically induces actin remodeling in order to promote efficient virion production. Beta- and γ-cytoplasmic actin recruitment could substitute for that of the endosomal sorting complex required for transport (ESCRT) mobilized by other enveloped viruses but apparently not used by Sendai virus.     

γ-catenin alleviates cardiac fibrosis through inhibiting phosphorylation of GSK-3β

Cardiac fibrosis is a common pathological change of many cardiovascular diseases. β-catenin has been shown to promote fibrosis. However, the precise role of its homolog γ-catenin in the process of fibrosis remains largely unclear. In this study, we found that the expression of γ-catenin was significantly decreased in angiotensin Ⅱ (Ang Ⅱ)-induced cardiac fibrosis model, contrary to most reports of β-catenin. Overexpression of γ-catenin in cardiac fibroblasts (CFs) significantly inhibited the expression of α-smooth muscle actin (α-SMA), whereas knocking down the expression of γ-catenin with siRNA promoted the occurrence of cardiac fibrosis. Mechanistically, γ-catenin could bind to GSK-3β to inhibit the phosphorylation of GSK-3β, therefore preventing cardiac fibrosis. Our study shows that γ-catenin is an important protective factor in cardiac fibrosis, which provides a new potential target for the treatment of cardiac fibrosis.