Identification of peptides presented through the MHC-II of dendritic cells stimulated with Mycobacterium avium

Mycobacterium avium (M. avium) represents a species of concern, because of its ability to modulate the host’s innate immune response, and therefore influence trajectory of adaptative immunity. Since eradicative response against mycobacteria, and M. tuberculosis/M. avium, relies on peptides actively presented on a Major Histocompatibility complex-II (MHC-II) context, we assessed paradoxical stimulation of Dendritic Cell resulting on immature immunophenotype characterized by membrane minor increase of MHC-II and CD40 despite of high expression of the pro-inflammatory tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in supernatants. Identification of M. avium leucine rich peptides forming short α-helices shutting down Type 1T helper (Th1), contribute to the understanding of immune evasion of an increasingly prevalent pathogen, and may provide a basis for future immunotherapy to infectious and non-infectious disease.     

Potential preventive strategies and therapies in urinary tract infection

There are perhaps five strategies either presently advocated or under investigation for prevention of recurrent urinary tract infection (UTI): antibiotics, including natural peptides; functional foods; vaccines; probiotics; and miscellaneous, including avoidance of spermicides and maintenance of good hygiene. It is not possible to state the proportion of patients using antibiotics versus foods such as cranberry or using alternative approaches such as avoidance of spermicides. The majority of women who are referred to specialists will be prescribed long-term, low-dose antibiotics. However, given the magnitude of the problem, it is safe to state that large numbers of women are at least experimenting with alternative remedies such as drinking of cranberry juice or ingestion of herbal remedies with a view to enhancing their immune response. Vaccine development remains a long way from human use and has yet to be developed for organisms other than Escherichia coli. The use of probiotics to restore the normal vaginal flora and provide a competitive bacterial barrier to pathogens is close to becoming available as an alternative preventive approach. The next decade should see the introduction of new methods for reduction of the high incidence of UTI and better management of recurring urogenital infections.     

肠三叶因子对新生鼠缺氧肠损伤模型白细胞介素8、丙二醛的影响及意义

目的　研究肠三叶因子 (intestinaltrefoilfactor,ITF)对坏死性小肠结肠炎 (necrotizingenterocolitis,NEC)新生大鼠的肠粘膜中白细胞介素 8(interleukin 8,IL 8)及丙二醛 (malondialdehyde,MDA)含量的影响 ,探讨ITF对NEC是否有保护作用。　方法　建立NEC模型 ,对新生 1日龄Wistar大鼠予 10 0 %二氧化碳 ,5min后再予 10 0 %氧气 ,5min后放回母鼠身边喂养 ,第 4天处死大鼠取肠道组织待检。新生鼠 32只随机分为四组 ,A组为NEC模型后腹腔注射ITF 0 .5mg ;B组为NEC模型后皮下注射ITF 0 .2mg ;C组为NEC模型组 ;D组为正常对照组。取近回盲段 1～ 2cm肠道组织固定包埋、切片、HE染色光镜下作病理学检查 ,其他肠道组织制备组织匀浆取上清液用放射性免疫法检测IL 8,用生化法检测MDA的含量。　结果　A、B组IL 8的含量 [pg (mg·pro) ]各为 2 9.72 2± 7.134、30 .5 12± 8.2 30 ,均较C组 39.379± 4 .4 2 0低 (P <0 .0 5 ) ,而与D组 2 3.92 2± 6 .16 8比较 ,差异无显著性 (P >0 .0 5 ) ;A、B组MDA的含量 [nmol (mg·pro) ]各为 2 .2 6 7± 0 .2 6 7、2 .15 4± 0 .30 1,较C组 3.378± 0 .835低 (P <0 .0 1) ,与D组 2 .2 2 5± 0 .4 4 3比较 ,差异无显著性 (P >0 .0 5 )。C组HE染色切片见肠壁的损伤轻重不一 ,有的     

体外培育牛黄与天然牛黄指纹图谱的比较研究

目的：研究、比较体外培育牛黄与天然牛黄的指纹图谱。方法：利用TOFMS、HPIEJMS技术研究、比较体外培育牛黄与天然牛黄中肽类、胆汁酸类和胆红素类3类成分的指纹图谱。结果：体外培育牛黄与天然牛黄3类成分的指纹基本一致，但各成分间的相对含量有差异。结论：10批体外培育牛黄的指纹图谱有较好的一致性，说明体外培育牛黄的质量稳定。4批天然牛黄的指纹图谱，尤其是胆汁酸类成分的指纹图谱差异明显，说明天然牛黄由于来源不同，导致质量不够稳定.     

重组人Ⅱ型胶原250-270多肽的表达、纯化和鉴定

目的:表达与纯化重组人Ⅱ型胶原250-270多肽(rhCⅡ250-270),鉴定并确认rhCⅡ250-270多肽与预期的相符。方法:在E.coli BL 21中表达rhCⅡ250-270多肽,使用亲和层析法分离纯化。用限制性酶切、聚合酶链式反应(PCR)、基因序列测定、琼脂糖凝胶电泳、聚丙烯酰胺凝胶电泳(SDS-PAGE)和免疫印迹等方法在基因和蛋白水平上对rhCⅡ250-270多肽进行鉴定。结果:纯化的rhCⅡ250-270多肽,大小约43 kD,纯度为89.3%。E coRⅠ和SalⅠ双酶切法和PCR法鉴定测得DNA大小约为500bp和650bp,核苷酸序列测定证实基因DNA序列与设计的完全相符。SDS-PAGE显示rhCⅡ250-270多肽目的蛋白条带的大小约为43 kD,W estern B lotting证实GST融合蛋白上存在CⅡ片段。结论:表达和纯化rhCⅡ250-270多肽与预期的相符,并发现此多肽具有较强的免疫原性。     

微囊藻毒素致毒机理的研究进展

微囊藻毒素是一种单环七肽毒素，主要由微囊藻产生。近年来有许多研究表明微囊藻毒素能诱导细胞凋亡、氧化应激和线粒体功能的改变，并发现凋亡相关蛋白Bcl-2蛋白家族和P53在其中起重要作用。     

An Update on the Status of Potent Inhibitors of Metallo-β-Lactamases

The production of metallo-β-lactamases is the most important strategy by which pathogenic bacteria become resistant to currently known β-lactam antibiotics. The emergence of these enzymes is particularly concerning for the future treatment of bacterial infections. There are no clinically available drugs capable of inhibiting any of the metallo-β-lactamases, so there is an urgent need to find such inhibitors. In this review, an up-to-date status of the inhibitors investigated for the inhibition of metallo-β-lactamases has been given so that this rich source of structural information of presently known metallo-β-lactamases could be helpful in generating a broad-spectrum potent inhibitor of metallo-β-lactamases.     

Preparation of cell-affinity adsorbents by immobilization of peptides to Sephadex G-10

In this study, affinity adsorbents for the binding of activated blood platelets and endothelial cells were prepared from Sephadex G-10 by immobilization of peptides, derived from the cell-adhesive amino acid sequence RGD (arginine-glycine-aspartic acid). Derivatization of Sephadex G-10 was accomplished by sequential coupling of specific dipeptides (RG and DV) (V = valine) and by coupling of the RGD-containing hexapeptide GRGDSP (S = serine, P = proline). Two types of gel were prepared by sequential coupling, designated as G10 (acetone) and G10 (dimethylformamide) (G10 (DMF)), containing peptides which had been coupled to the outer side of the beads and throughout the porous beads, respectively. The binding capacity of the prepared Sephadex-derivatives amounted up to 2 x 10⁹ human blood platelets per millilitre GRGDV-Sephadex at immobilized peptide concentrations, that were in the nanomole range (per millilitre packed gel) and which differed a factor 10 between G10 (acetone) and G10 (DMF). In a second series of experiments, different amounts of the hexapeptide GRGDSP were coupled to carboxylated Sephadex G-10 and carboxylated Sepharose CL 6B. The binding of human umbilical vein endothelial cells to the resulting materials was studied. Up to 10⁶ endothelial cells attached per ml GRGDSP-derivatized hydrogel at peptide concentrations of 15 nmol GRGDSP/ml Sephadex and at ±300 nmol GRGDSP/ml Sepharose. Substitution of the arginine residue of the RGD-sequence by glutamine abolished the cell-binding activity of the immobilized peptide towards activated blood platelets but not towards endothelial cells. From the results of this study it can be concluded that small peptides can be coupled to the outer side of the porous Sephadex beads, resulting in high effective ligand densities for cell-affinity applications. In this respect, Sephadex G-10, derivatized according to 'the acetone method', is a good alternative for polystyrene and other solid phase materials.     

Clonality and specificity of cryoglobulins associated with HCV: pathophysiological implications

Background/Aims: Hepatitis C virus (HCV) infection plays a central role in the pathogenesis of mixed cryoglobulinemia through molecular mechanisms which remain to be elucidated. The aim of this study was to investigate the role of antibody responses to HCV in the pathogenesis of cryoglobulinemia through characterization of the anti-HCV specificity and immunochemical characteristics of the immunoglobulins involved in cryoprecipitation.Methods: Sera from 50 consecutive patients with chronic HCV infection (RNA positive) were screened for the presence of cryoglobulins. The two major components of cryoprecipitates, IgM rheumatoid factors and IgG, were separated by high performance liquid chromatography and analyzed for immunochemical composition by immunoblotting and antibody specificity by ELISA and immunoblotting using recombinant HCV proteins and synthetic peptides as antigens.Results: Cryoprecipitates were observed in 27 patients and characterized by immunofixation: 13 (48%) were classified as type II and 14 (52%) as type III. Monoclonal immunoglobulins were detected by immunoblotting in 20 cryoprecipitates: IgM in 14 samples and IgG in 14, which a clear preponderance of IgG3 (). Specificity studies on sera and purified IgM and IgG fractions from cryoprecipitates revealed enrichment in cryoglobulins, predominantly polyclonal IgG1, reactive with the HCV structural proteins, whereas specificities for nonstructural viral proteins were relatively less represented compared to whole serum. No restricted pattern of fine specificity was observed. IgG3 subclass was apparently not involved in HCV nucleoprotein binding.Conclusions: Our findings do not support a direct link between monoclonal cryoglobulins and immune response to HCV. According to the proposed pathogenetic model, HCV infection can induce the formation of cryoprecipitable rheumatoid factors, sustain their production, and eventually lead to monoclonal B-cell expansion through several cooperative mechanisms.