HbA1 in assessment of metabolic control in diabetic BB/E rats

Summary Estimations of HbA₁ levels have been used to assess long-term glycaemic control in spontaneously diabetic BB/E rats. The degree of metabolic control achieved by once daily insulin injections and continuous insulin infusion by osmotic minipump was compared. Citrate gel electrophoresis of lysed erythrocytes, previously washed and incubated in 0.9% NaCl, gave accurate HbA₁ values without interference from either abnormal Hb variants or labile glycosylation products. Over a 12 week period there was no significant difference in the mean random weekly plasma glucose concentrations between diabetic rats maintained on insulin injections or continuous infusion therapy. The HbA₁ values in the injection-treated animals remained unchanged throughout the study period (mean±SEM = 5.1±0.1%). Diabetic rats treated by osmotic minipump showed a steady decline in values over the same period (4.1±0.1%; p<0.001 vs injected rats) but levels remained higher than those recorded in non-diabetic control rats (2.9±0.01%; p<0.001 vs pump-treated rats). These differences in HbA₁ were reflected in the plasma glucose values obtained during a 30 h glucose profile performed after six weeks of insulin therapy. Diabetic rats on injection therapy showed considerable diurnal variation in plasma glucose concentration (5.5–11.2 mmol/l; mean 8.9±0.5) but continuous insulin infusion eliminated the fluctuations giving a significantly lower mean glucose level over the 30 h period (7.3±0.1 mmol/l; p<0.005). HbA₁ levels show a poor correlation with random plasma glucose estimations (r=0.43) but provide a simple and accurate assessment of long-term glycaemic control without the need for multiple 24 h glucose profiles.     

全反式维甲酸对球囊损伤大鼠胸主动脉内皮后内膜增生及PDGF-BB表达的影响

目的　研究全反式维甲酸 (all transretinoicacid ,ATRA)对球囊损伤大鼠胸主动脉内皮后内膜增生及血小板衍生生长因子B(BDGF BB)表达的影响。方法　球囊剥脱大鼠胸主动脉内皮 ,并随机将大鼠分为手术组、ATRA治疗组及对照组 ,各组大鼠均于术前 4d灌胃 ,分别在术后 2、7、14和 18d处死大鼠并摘除胸主动脉。通过组织学检查和免疫组化技术检测内膜增生情况、PDGF BB的表达及ATRA[30mg/ (kg·d) ]灌胃对它们的影响。结果　 (1)对照组及内皮损伤后 2d均无血管内膜增厚 ,7d内膜开始增生 ,2 8d血管平滑肌细胞 (VSMCs)的增殖减弱 ,但细胞外基质增加 ,内膜继续增生 ;(2 )PDGF BB的表达于术后 2d开始升高 ,至 14d达高峰 ;(3)使用ATRA后内膜增生程度及PDGF BB的表达明显降低。结论　ATRA可有效地抑制血管损伤后内膜增生 ,其机制可能是通过抑制PDGF BB表达 ,从而抑制血管平滑肌细胞增殖     

血小板衍生生长因子在脑血管痉挛发生中的作用

目的：探讨血小板衍生生长因子BB（PDGF－BB）在蛛网膜下腔出血（SAH）后的表达及其对正常脑血管的影响。方法：在兔SAH模型上利用免疫组化方法观察了脑血管壁的PDCF－BB的表达情况；同时观察了枕大池内注入PDGF－BB对正常脑血管的影响。结果：SAH后48h脑基底动脉明显痉挛，痉挛血管壁的PDGF－BB表达增多；枕大池内注入PDGF－BB后，脑基底动脉出现以注入后24h为高峰的迟发性脑血管缩窄。结论：PDGF－BB在脑血管痉挛发生、发展的病理过程中具有重要意义。     

Characterization and application of three novel monoclonal antibodies against human 4-1BB: distinct epitopes of human 4-1BB on lung tumor cells and immune cells

4-1BB, a member of the tumor necrosis factor receptor (TNFR) superfamily, is a costimulatory receptor that is primarily expressed on activated T cells and professional antigen-presenting cells. In this study, the expression pattern of 4-1BB on immunology cells and tumor cells was explored by flow cytometry using newly generated three anti-4-1BB monoclonal antibodies (mAbs; 6F9, 7D6, and 1G11), which bind to distinct 4-1BB epitopes. Compared with the available 4-1BB mAb 4B4-1 that recognized 4-1BB on activated T cells and monocytes, the novel mAbs also could recognize 4-1BB on some cancer cell lines, particularly on lung cancer cell lines such as SPC-A-1, H446, H460, and H1299 by flow cytometry analysis, western blot, and RT-PCR. Immunohistochemistry staining showed the 4-1BB was expressed on lung tumor tissue (33/35) but not on normal lung tissue (3/3). It was determined that 4-1BB was strictly expressed on lung cancer cells, which may provide information on the 4-1BB signal in tumor immunology mechanism.     

Co-stimulation with 4-1BB ligand allows extended T-cell proliferation, synergizes with CD80/CD86 and can reactivate anergic T cells

Activation of T cells requires co-stimulation, in addition to signals through the antigen-receptor complex. Antigen encounter without adequate co-stimulation results in T-cell desensitization or anergy, a mechanism of peripheral tolerance and an apparent obstacle to cancer immunotherapy. One important co-stimulatory pathway involves CD28 engagement by CD80 or CD86. However, other ligand-receptor pairs can also provide co-stimulation and may have important functions modulating the immune response. Previous reports indicated that co-stimulation using 4-1BB ligand (4-1BBL) or agonistic anti-4-1BB antibodies could prolong T-cell responses, avoid activation-induced cell death and promote anti-tumour responses in mice. To further investigate the potential for cancer immunotherapy, we studied the effects of CD80/CD86 and 4-1BBL in repeated stimulation of human T cells and asked whether 4-1BBL might be capable of reversing anergy. We expressed CD80, CD86 and 4-1BBL in A549 lung carcinoma cells using adenovirus vectors and co-cultured these with human T cells stimulated with anti-CD3 antibody. Proliferation co-stimulated by CD80 or CD86 was transient; however, 4-1BBL-co-stimulated cultures continued to proliferate for up to 5 weeks, with repeated stimulation. Combined co-stimulation with CD80/CD86 and 4-1BBL also allowed continuous proliferation at a faster rate than either signal alone. Co-stimulation with 4-1BBL did not suppress expression of the inducible, inhibitory CD80/CD86R, CTLA-4. Significantly, we show that T cells that had become non-responsive to anti-CD3, either alone or together with CD80/CD86 co-stimulation, and thus were anergic, could be reactivated to proliferate when costimulated with 4-1BBL, either alone or combined with CD80/CD86.     

CD28-independent,TRAF2-dependent Costimulation of Resting T Cells by 4-1BB Ligand

4-1BB ligand (4-1BBL) is a member of the tumor necrosis factor (TNF) family expressed on activated antigen-presenting cells. Its receptor, 4-1BB, is a member of the TNF receptor family expressed on activated CD4 and CD8 T cells. We have produced a soluble form of 4-1BBL using the baculovirus expression system. When coimmobilized on plastic with anti-CD3, soluble 4-1BBL induces interleukin (IL)-2 production by resting CD28⁺ or CD28⁻ T cells, indicating that 4-1BBL can function independently of other cell surface molecules, including CD28, in costimulation of resting T cell activation. At low concentrations of anti-CD3, 4-1BBL is inferior to anti-CD28 in T cell activation. However, when 4-1BB ligand is provided together with strong TCR signals, then 4-1BBL and anti-CD28 are equally potent in stimulation of IL-2 production by resting T cells. We find that TNF receptor–associated factor (TRAF)1 or TRAF2 associate with a glutathione S-transferase–4-1BB cytoplasmic domain fusion protein in vitro. In T cells, we find that association of TRAF1 and TRAF2 with 4-1BB requires 4-1BB cross-linking. In support of a functional role for TRAF2 in 4-1BB signaling, we find that resting T cells isolated from TRAF2-deficient mice or from mice expressing a dominant negative form of TRAF2 fail to augment IL-2 production in response to soluble 4-1BBL. Thus 4-1BB, via the TRAF2 molecule, can provide CD28-independent costimulatory signals to resting T cells.     

A systematic description of the post-EMR defect to identify risk factors for clinically significant post-EMR bleeding in the colon

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