N-Alkoxycarbonyl-glutamic and aspartic acids

N-Alkoxycarbonylaminodicarboxylic acids were reacted in dichloromethane with N-ethyl-N′-(dimethylaminopropyl)carbodiimide hydrochloride, and with methyl chloroformate in the presence of N-methylmorpholine. Removal of secondary products by washing the mixtures with aqueous solutions gave good yields of the pure crystalline internal anhydrides. Anhydrides of N-benzyloxycarbonyl- (Z) and N-9-fluorenylmethoxycarbonyl-(Fmoc) L-glutamic and L-aspartic acids and of N-tert.-butoxycarbonyl-L-aspartic acid were prepared in this way. The compounds were shown to be amenable to normal phase high-performance liquid chromatography (NP-HPLC) on a CN-column using tert.-butanol-hexane as solvent. The products of the reactions of Z- and Fmoc-glutamic acid with hot acetic anhydride were examined by nuclear magnetic resonance and NP-HPLC before and after methanolysis in an attempt to establish if any of the corresponding pyroglutamates were formed. The reaction of Fmoc-chloride with Fmoc-glutamate was examined for the same reason. It is concluded that the side product generated during the reaction of Fmoc-chloride with glutamic acid which is used for analysis of the latter is the N-protected internal anhydride and not the pyroglutamate as reported in the literature.     

Ⅴ-Ti催化剂低氧催化氧化邻二甲苯制苯酐——Ⅱ.TiO_2晶体结构及助剂作用的影响

研究了V-Ti体系中TiO_2晶体结构与催化活性的联系,本系统中,当焙烧温度超过650℃,由于TiO_2由锐钛矿型转变为金红石型,使催化活性降低。助剂作用的ESCA、XRD、LRS研究表明,与通常V-Ti系催化剂不同,本催化剂由于助剂的作用,使V=O键减弱而利于活化;且随K助剂含量增加,V_2O_(4.33)晶胞的001面取向优化加强,更宜于催化活性的充分显示。     

丁二酸酐交联羟基超支化聚(胺-酯)的反应及其交联膜的性质

以丁二酸酐(SA)为交联剂研究了端羟基超支化聚(胺-酯)(HPAE)的交联反应和交联膜的制备。结果表明:SA与HPAE的交联反应分为两个阶段,可以采用溶液法低温涂膜及高温交联得到HPAE/SA交联膜;改变SA的用量可控制膜的交联度,HPAE/SA交联膜的拉伸强度随SA用量的增大而提高,最高可达59.60 M Pa,膜表面的水接触角小于74.3°。     

顺丁烯二酸水溶液的热反应动力学

研究了不同温度、浓度条件下，顺丁烯二酸（顺酸）非催化反应网络，即顺酸可生成反丁烯二酸（反酸）和苹果酸，反酸与苹果酸存在可逆反应。建立了该反应网络的动力学模型。测定了不同反应条件下顺酸、反酸和苹果酸浓度随时间变化的规律，据此，动力学参数进行了估值。     

Bronchial hyperresponsiveness, epithelial damage, and airway eosinophilia after single and repeated allergen exposure in a rat model of anhydride-induced asthma

Bronchial hyperresponsiveness (BHR) and damage of the epithelium, as well as eosinophilia in the airway wall, induced by trimellitic anhydride (TMA) in sensitized brown Norway rats were studied. Rats were challenged once or seven times with aerosol of TMA conjugated to rat serum albumin (TMA-RSA) 3 weeks after intradermal TMA sensitization. Airway responsiveness (-log PC₃₀₀ of acetylcholine i.v.) was measured 24 h after allergen challenge. Epithelial lesion and eosinophil infiltration in the airway walls were quantified under light microscopy, and TMA-specific IgE and IgG in serum were evaluated with ELISA. High levels of TMA-specific IgE and IgG were found in all rats in the sensitized groups compared to nonsensitized groups ( P < 0.001). Repeated allergen challenges of 0.03% TMA-RSA for 7 consecutive days enhanced the level of TMA-specific IgG, compared to single challenge ( P < 0.05). Single allergen challenge of 0.3% TMA-RSA had a nonsignificant tendency to produce BHR in sensitized rats compared to nonsensitized rats ( P =0.06). However, repeated allergen challenges (0.003% and 0.03% TMA-RSA for 7 consecutive days) produced significant BHR in sensitized rats ( P < 0.05). Furthermore, repeated low-dose (0.003%) TMA-RSA challenge produced more BHR than a 10 times higher single dose (0.03%) ( P < 0.05). Slight damage of the airway epithelium was seen in sensitized and repeat-challenged groups. However, bronchial eosinophilia was found in the sensitized and single-challenged groups, but not in nonsensitized nonchallenged, and sensitized repeat-challenged groups ( P < 0.005). We conclude that the brown Norway rat can be sensitized with TMA, and that repeated low-dose allergen challenges produce slight epithelial damage and BHR which is independent of ongoing eosinophilia in the airway wall.     

Degradable poly(anhydride ester) implants: effects of localized salicylic acid release on bone

Degradable poly(anhydride ester) implants in which the polymer backbone breaks down into salicylic acid (SA) were investigated. In this preliminary work, local release of SA from the poly(anhydride esters), thus classified as ‘active polymers', on healthy bone and tissue was evaluated in vivo using a mouse model. Degradable polyanhydrides that break down into inactive by-products were used as control membranes because of their chemical similarity to the active polymers. Small polymer squares were inserted over the exposed palatal bone adjacent to the maxillary first molars. Active polymer membranes were placed on one side of the mouth, control polymers placed on the contra lateral side. Intraoral clinical examination showed that active polymer sites were less swollen and inflamed than control polymer sites. Histopathological examination at day 1 showed essentially no difference between control and active polymers. After 4 days, active polymer sites showed epithelial proliferation to a greater extent than the polyanhydride controls. After 20 days, active polymer sites showed greater thickness of new palatal bone and no resorptive areas, while control polymer sites showed less bone thickness as well as resorption including lacunae involving cementum and dentine. From these preliminary studies, we conclude that active polymers, namely poly(anhydride esters), stimulated new bone formation.     

The association between serum levels of Th cytokines and rhinoconjunctivitis caused by methyltetrahydrophthalic anhydride

Background There are few epidemiologic studies on the association between serum levels of T helper (Th) cytokines and allergic symptoms caused by sensitizing agents.
Methods A population of 147 workers from two condenser plants using epoxy resin with methyltetrahydrophthalic anhydride (MTHPA) underwent a questionnaire survey and serologic investigations. Total and MTHPA-specific IgE levels were measured by the Pharmacia CAP System, and serum levels of interleukin (IL)-4, IL-13, and interferon-gamma (IFN-γ) by enzyme immunoassay.
Results A significant association was found between work-related eye and nasal symptoms and a range of atopic characteristics, including the frequency of positive specific IgE, specific and total IgE levels, and IL-4 levels. A positive correlation was observed between levels of IL-4 and IL-13 (r=0.42). Furthermore, multiple logistic analysis revealed significant contributions of specific IgE and I H3 to the work-related symptoms. A similar but nonsignificant association was also found for IL-4 (P=0.07). On the other hand, a multiple regression model with specific IgE levels as a dependent variable showed a significant association with total IgE, but not with IL-4, IL-13, and IFN-γ.
Conclusions These results suggest that work-related eye and nasal symptoms are closely related to specific IgE antibodies, and that allergic responses, mediated by IgE, to MTHPA may lead to a shift in the balance between Thl and Th2 cells.     

具有多重玻璃化转变的梳状聚合物的合成,表征和导电性：侧链 …

以分子量为５５０的聚乙二醇单甲醚为侧链,苯乙烯／马来酸酐共的为骨架,合成了苯乙烯／马来酸酐共聚物多缩乙二醇酯。用红外光谱、元素分析、ＤＳＣ、热失重等方法,对合成条件、产物结构和性能进行了研究。结果表明：反应严格按照反应方程进行,精制产物是非晶的梳状聚合物。玻璃化转变温度为３０．６８℃,分解温度为１２０℃。对动态这性能及其锂盐复合物离子导电性进行了研究,表明α转变温度和β转变温度分别是２８℃他－４７