Syndiotactic polymerization of styrene with cyclopentadienyltribenzyloxytitanium/methylaluminoxane catalyst

Syndiotactic polystyrene was efficiently prepared in the presence of a homogeneous catalyst composed of (η⁵-cyclopentadienyl)tribenzyloxytitanium and methylaluminoxane (MAO) as a cocatalyst. Influences of various polymerization conditions, e.g., [Ti]. [MAO], [St], temperature and the content of retained trimethylaluminium (TMA) in MAO on the catalytic activity, syndiotacticity and molecular weight of the polymer were studied. It was found that the retained TMA plays an important role in the polymerization. Lowering the retained TMA content in MAO decreases the activity of the catalyst remarkably. Addition of external alkylaluminium (TMA or triisobutylaluminium) into the catalyst system with MAO containing low amounts of retained TMA promotes styrene polymerization.     

植物血凝素(PHA)对小鼠骨髓粒—单祖细胞增殖的影响

用体外琼脂培养法研究了PHA对小鼠骨髓CFU-GM的影响,结果表明,小鼠经腹腔注射PHA后,对小鼠CFU-GM产率和自杀率的影响随PHA的剂量不同而异,20～40mg/kg的PHA能明显提高CFU-GM的产率,其作用时间维持3天,剂量大于50mg/kg,可抑制CFU-GM产率。PHA组自杀率较对照组明显提高,提示适量的PHA在体内可促进小鼠CFU-GM的增殖,使更多的CFU-GM由Go期进入S期。将PHA直接加入无CSF的培养体系中,未见集落生长。此项结果提示PHA可能通过间接机制而非直接作用于CFU-GM。     

Low-grade squamous intraepithelial lesions: Cytologic predictors of biopsy Confirmation

One hundred and seven smears demonstrating a low-grade squamous intraepithelial lesion (LSIL) were analyzed for features predicting subsequent biopsy confirmation. Twelve (29%) of 41 smears showing few LSIL cells were biopsy confirmed compared to 33 (60%) of 55 containing an intermediate number of LSIL cells and 9 (82%) of 11 displaying many LSIL cells (P < 0.002). Thirty-seven (47%) of 78 smears showing mainly condylomatous atypia (CA), 7 (54%) of 13 revealing predominantly cervical intraepithelial neoplasia 1 (CIN 1), and 10 (63%) of 16 displaying both CA and CIN 1 were histologically confirmed (N.S.). Biopsy confirmation was obtained in 35 (65%) of 54 women whose repeat smears obtained at colposcopy demonstrated SIL compared to four (15%) of 26 patients whose repeat smears were normal or contained atypical squamous cells of undetermined significance (P < 0.001). These results suggest that the number of diagnostic cells in an LSIL smear predicts biopsy confirmation and affirm the validity of combining CA and CIN 1 under the category of LSIL in the Bethesda System. © 1994 Wiley-Liss, Inc.     

Nucleolar localization of non-structural protein 3b, a protein specifically encoded by the severe acute respiratory syndrome coronavirus

The open reading frame 3 (ORF3) of the severe acute respiratory syndrome coronavirus (SARS-CoV) genome encodes a predicted 154-amino acid protein, which lacks similarities to any known protein, and is named 3b. In this study, it was shown that 3b protein was predominately localized to nucleus with EGFP tag at its N- or C-terminus. The localization patterns were similar in different transfected cells. Immuno-fluorescence assay revealed that 3b protein was co-localized well with C23 in nucleolus. C23, B23 and fibrillarin all are important nucleolar proteins, which localize in the region of the nucleolus. Co-transfection of p3b-EGFP with pC23-DsRed, pB23-DsRed and pfibrillarin-DsRed further confirmed 3b's nucleolus localization. With construction of serial truncated mutants of 3b, a region (residues 134-154 aa) responsible for nucleolar localization was determinated in 3b protein. These results provide a new insight for further functional studies of SARS-CoV 3b protein.     

磁性阿霉素纳米微球的制备及在高频磁场中的发热研究

制备一种在高频磁场中能感应发热的用于治疗肿瘤的阿霉素纳米微球，研究其在磁场中的热效应。用超声搅拌冷冻干燥的方法制备药物微球，平均粒径200nm左右。电镜观察其形态为球囊状。将其置于不同介质中于高频磁场中测其温度变化值，实验表明该微球在交变磁场中使介质升温。升温速度与平稳时的温度和微球的量及磁场强度成正比，介质流动性好，升温快。     

Current trends and new approaches in the management of diabetes mellitus

Current trends in the management of type 2 diabetes mellitus, based on the 20-year United Kingdom Prospective Diabetic Study, include intensive treatment to control the blood glucose level and blood pressure in order to prevent or delay microvascular and cardiovascular complications. In the new millennium, type 2 diabetes will become epidemic in developing countries. If diabetes were to develop in 10% of the 1.2 billion population of China, the expense of intensive treatment would be immense. Laboratory tests are useful for detecting risk factors before the onset of the disease and convincing the general public to take preventive measures. Glucose tolerance testing is one of these tests. When glucose tolerance is impaired, 25% of beta-cell function is lost. Determining the plasma proinsulin level is another useful evaluation; impaired glucose tolerance accompanied by increased plasma proinsulin level is indicative of an enhanced risk that type 2 diabetes will develop within 5 years. Educating the public about eating a healthy diet and exercising may prevent the development of diabetes and thereby reduce the global prevalence of type 2 diabetes.     

The Secreted Larval Acidic Proteins (SLAPs) of Onchocerca spp. are encoded by orthologues of the alt gene family of Brugia malayi and have host protective potential

Onchocerca volvulus is a tissue-dwelling, vector-borne nematode parasite of humans and the causative agent of onchocerciasis, or 'River Blindness'. Resistance to infection is associated with immune responses to the infective, third-stage (L3) larvae. The antigens of greatest interest for their vaccine potential are surface and secreted molecules. We have previously identified a family of Secreted Larval Acidic Proteins (SLAPs) from the L3 larvae of O. volvulus by biosynthetic labelling. Here, we provide further characterisation of these molecules following cloning and expression of the corresponding cDNAs. Using protein sequencing, we show that SLAPs are members of the alt gene family, first described in the lymphatic filarial parasite, Brugia malayi. Ov-ALT-1 and Ov-ALT-2 correspond with 20 and 18kDa SLAPs. Both proteins are highly acidic and related by sequence, differing chiefly in an 8-amino acid deletion from Ov-ALT-2. By immunochemistry, we confirm that Ov-ALTs are highly stage-specific, being expressed exclusively in late L2 and L3 larvae during growth in the vector. They are synthesised and stored in the glandular oesophagus. Secretion is triggered by the resumption of development in the definitive host and occurs via the pseudocoelom and cuticle. Serological responses in humans to recombinant Ov-ALT-1 indicate that the level of IgG production may be governed by the force of transmission but does not overtly reflect infection status. Immunisation of mice with recombinant Ov-ALT-1 resulted in a modest level of protection against challenge with O. volvulus L3 larvae (P = 0.036). We conclude that Ov-ALT genes, like those of other filariae, are of interest from the standpoint of parasite transmission and infectivity. They may also offer promise as components of a future sub-unit vaccine should the means to enhance protection be achieved.     

芦荟大黄素对豚鼠皮肤黑色素细胞NOS的影响--免疫组织化学研究

目的探讨豚鼠皮肤黑色素细胞在大黄有效成分的作用下,一氧化氮合酶(Nitric OxideSynthse;NOS)表达的变化,阐明大黄在活体皮肤中对黑素细胞的有效作用浓度和作用机制.方法将21只雄性豚鼠随机分成对照组及5个实验组,用芦荟大黄素5种浓度对局部皮肤皮下注射处理,48小时后取材,免疫组织化学方法(SABC)法显示NOS的表达,用光学显微镜和图象分析仪对结果进行统计分析.结果芦荟大黄素作用下,表皮黑素细胞NOS表达明显减少,光密度明显下降(P<0.05);不同浓度药物作用之间无显着差异(P＞0.05),加注侧与未加注侧之间无显著差异.结论芦荟大黄素对黑色素细胞NOS的表达具有调节作用,提示大黄对黑素细胞的调节是经NO信号介导途径,为大黄的临床应用提供实验依据.     

Episomal and stable expression of the luciferase reporter gene for quantifying Leishmania spp. infections in macrophages and in animal models

We have expressed the reporter firefly luciferase gene (LUC) in Leishmania donovani and Leishmania major either as part of episomal vectors or integrated into the parasite genome under the control of their respective ribosomal promoter regions. An excellent linear correlation between parasite number and luciferase activity was observed with all the transfectants. LUC-expressing recombinant parasites were useful to monitor Leishmania spp. infections in macrophages or in animal models. For prolonged growth in absence of drug selection, such as within animal models, quantitation of parasites is more reliable when the reporter gene LUC is stably integrated in the parasite genome. These recombinant strains should be useful tools to monitor Leishmania growth under a number of conditions.