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排序方式: 共有631条查询结果,搜索用时 31 毫秒
21.
《Journal of biomaterials science. Polymer edition》2013,24(8):675-693
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. 相似文献
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Mario U. Mondelli Irene Zorzoli Antonella Cerino Agostino Cividini Morena Bissolati Laura Segagni Vittorio Perfetti Ernesto Anesi Pietro Garini Giampaolo Merlini 《Journal of hepatology》1998,29(6):879-886
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. 相似文献
24.
《Vaccine》2015,33(2):396-402
BackgroundFP-01.1 is a novel synthetic influenza A vaccine consisting of six fluorocarbon-modified 35-mer peptides that encapsulate multiple CD4+ and CD8+ T-cell epitopes and is designed to induce an immune response across a broad population.MethodsFP-01.1 was evaluated for safety and immunogenicity in a randomised, double-blind, placebo-controlled, dose-escalation, phase I clinical study in healthy adult volunteers (n = 49). IFNγ ELISpot assays and multicolour flow cytometry were used to characterise the immune response.ResultsFP-01.1 was safe and well tolerated at all doses tested with a similar adverse event profile in actively vaccinated subjects compared with controls. Maximum immunogenicity was in the 150 μg/peptide dose group where a robust response (243 spots/million PBMC) was demonstrated in 75% subjects compared with 0% in placebo controls. All six peptides were immunogenic. FP-01.1 induced dual CD4+ and CD8+ T cell responses and vaccine-specific T cells cross-recognise divergent influenza strains.ConclusionsThis first-in-human study showed that FP-01.1 has an acceptable safety and tolerability profile and generated robust anti-viral T cell responses in a high proportion of subjects tested. The results support the further clinical testing of FP-01.1 prior to clinical, proof-of-concept, live viral challenge studies. 相似文献
25.
心肌肽素对豚鼠心室肌细胞内向整流钾电流的影响 总被引:6,自引:1,他引:6
目的研究心肌肽素对豚鼠心室肌细胞内向整流钾电流(IK1)的影响,探讨心肌肽素抗心律失常的作用机制。方法用急性酶解法分离豚鼠心室肌细胞,用标准的全细胞膜片钳技术,观察不同浓度的心肌肽素对内向整流钾电流的影响。结果在测试电压100mV的条件下,观察豚鼠心室肌细胞IK1内向电流对心肌肽素的影响。10μg/ml心肌肽素使IK1从给药前21.0±6.3pA/pF降低到给药后18.4±5.4pA/pF(P<0.05),抑制率为(20±3)%。50μg/ml心肌肽素使IK1从给药前22.8±5.5pA/pF降低到给药后16.0±3.8pA/pF(P<0.01),抑制率为(32±6)%。50μg/ml心肌肽素没有改变IK1的电流密度电压曲线形态。结论心肌肽素抑制豚鼠心室肌细胞IK1,可能是其抗心律失常作用的机理之一。 相似文献
26.
Maemu Petronella Gededzha Maphahlanganye Jeffrey Mphahlele Selokela Gloria Selabe 《Hepatitis monthly》2014,14(11)
Background:
Hepatitis C virus (HCV) is one of the major causes of cirrhosis and hepatocellular carcinoma with an estimation of 185 million people with infection. The E2 is the main target for neutralizing antibody responses and the variation of this region is related to maintenance of persistent infection by emerging escape variants and subsequent development of chronic infection. While both E1 and E2 are hypervariable in nature, it is difficult to design vaccines or therapeutic drugs against them.Objectives:
The objective of this study was to characterize genotype 5a E1 and E2 sequences to determine possible glycosylation sites, conserved B-cell epitopes and peptides in HCV that could be useful targets in design of vaccine and entry inhibitors.Patients and Methods:
This study was conducted through PCR amplification of E1 and E2 regions, sequencing, prediction of B-cell epitopes, analysis of N-linked glycosylation and peptide design in 18 samples of HCV genotype 5a from South African.Results:
Differences in the probability of glycosylation in E1 and E2 regions were observed in this study. Three conserved antigenic B-cell epitopes were predicted in the E2 regions and also 11 short peptides were designed from the highly conserved residues.Conclusions:
This study provided conserved B-cell epitopes and peptides that can be useful for designing entry inhibitors and vaccines able to cover a global population, especially where genotype 5a is common. 相似文献27.
Kyle V. Holmberg Mahsa Abdolhosseini Yuping Li Xi Chen Sven-Ulrik Gorr Conrado Aparicio 《Acta biomaterialia》2013,9(9):8224-8231
We developed a novel titanium coating that has applications for preventing infection-related implant failures in dentistry and orthopedics. The coating incorporates an antimicrobial peptide, GL13K, derived from parotid secretory protein, which has been previously shown to be bactericidal and bacteriostatic in solution. We characterized the resulting physicochemical properties, resistance to degradation, activity against Porphyromonas gingivalis and in vitro cytocompatibility. Porphyromonas gingivalis is a pathogen associated with dental peri-implantitis, an inflammatory response to bacteria resulting in bone loss and implant failure. Our surface modifications obtained a homogeneous, highly hydrophobic and strongly anchored GL13K coating that was resistant to mechanical, thermochemical and enzymatic degradation. The GL13K coatings had a bactericidal effect and thus significantly reduced the number of viable bacteria compared to control surfaces. Finally, adequate proliferation of osteoblasts and human gingival fibroblasts demonstrated the GL13K coating’s cytocompatibility. The robustness, antimicrobial activity and cytocompatibility of GL13K-biofunctionalized titanium make it a promising candidate for sustained inhibition of bacterial biofilm growth. This surface chemistry provides a basis for development of multifunctional bioactive surfaces to reduce patient morbidities and improve long-term clinical efficacy of metallic dental and orthopedic implants. 相似文献
28.
目的 探讨应用125I标记RGD多肽的放射性示踪方法测定RGD多肽在同种异体骨片表面的枝接密度的可行性。探寻RGD多肽反应浓度对表面密度的影响,获得RGD表面密度与反应浓度的关系曲线。方法 用放射性125I对人工合成的含RGD八肽(EPRGDNYR)进行标记反应,并测算比放射性。将标记后的125I-RGD作为放射性探针加入设计浓度分别为0.01 mg/ml、0.10 mg/ml、0.50 mg/ml、1.00 mg/ml、2.00 mg/ml、4.00 mg/ml的RGD反应液。以1-乙基-3-(3-二甲基氨丙基)碳二亚胺为交联剂,将预制的同种异体骨片置于不同设计浓度的RGD反应液中进行枝接反应。通过测定反应后的异体骨片的放射性和表面积,计算异体骨片表面RGD多肽的枝接密度,评价RGD多肽反应浓度对表面密度的影响并绘制二者的关系曲线。结果 通过放射密度γ-计数器的测定发现,125I能够成功标记于RGD多肽。以含有125I-RGD的不同设计浓度的RGD反应液与预制的同种异体骨片进行枝接反应后,发现同种异体骨片具有放射性,说明RGD多肽已经成功枝接于异体骨片。经分析发现RGD多肽的表面密度随反应浓度的增加而增加。结论 RGD多肽的表面密度与其反应浓度间定量相关,随反应浓度的增长,表面密度逐渐趋于饱和值。 相似文献
29.
Problems with measuring peripheral oxytocin: Can the data on oxytocin and human behavior be trusted?
Michael E. McCullough Patricia Smith Churchland Armando J. Mendez 《Neuroscience and biobehavioral reviews》2013
Research on the neurobiological and behavioral effects of oxytocin (OT), as well as on its possible therapeutic applications, has intensified in the past decade. Accurate determination of peripheral OT levels is essential to reach meaningful conclusions and to motivate, support and inform clinical interventions. Different, but concordant, methods for measuring plasma OT have been developed over the past four decades, but since 2004 several commercially available methods have been favored in research with humans. Evaluation of these methods reveals that they lack reliability when used on unextracted samples of human fluids, and that they tag molecules in addition to OT, yielding estimates that are wildly discrepant with an extensive body of earlier findings that were obtained using methods that are well validated, but more laborious. An accurate, specific, and readily available method for measuring OT that can be adopted as the standard in the field is urgently needed for advances in our understanding of OT's roles in cognition and behavior. 相似文献
30.