GCK-MODY diabetes as a protein misfolding disease: The mutation R275C promotes protein misfolding,self-association and cellular degradation

GCK-MODY, dominantly inherited mild hyperglycemia, is associated with more than 600 mutations in the glucokinase gene. Different molecular mechanisms have been shown to explain GCK-MODY. Here, we report a Pakistani family harboring the glucokinase mutation c.823C > T (p.R275C). The recombinant and in cellulo expressed mutant pancreatic enzyme revealed slightly increased enzyme activity (k_cat) and normal affinity for α-D-glucose, and resistance to limited proteolysis by trypsin comparable with wild-type. When stably expressed in HEK293 cells and MIN6 β-cells (at different levels), the mutant protein appeared misfolded and unstable with a propensity to form dimers and aggregates. Its degradation rate was increased, involving the lysosomal and proteasomal quality control systems. On mutation, a hydrogen bond between the R275 side-chain and the carbonyl oxygen of D267 is broken, destabilizing the F260-L271 loop structure and the protein. This promotes the formation of dimers/aggregates and suggests that an increased cellular degradation is the molecular mechanism by which R275C causes GCK-MODY.     

Human endothelial cell-based assay for endotoxin as sensitive as the conventional Limulus Amebocyte Lysate assay

Endotoxin, also known as lipopolysaccharide (LPS) produced by bacteria can be present in any liquid or on any biomaterial even if the material is sterile. Endotoxin in mammals can cause fever, inflammation, cell and tissue damage and irreversible septic shock and death. In the body, endothelial cells making up the blood vasculature and endothelial cells in vitro rapidly react to minute amounts of endotoxin resulting in a rapid induction of the cell adhesion molecule E-selectin. In this study we have used immunofluorescent staining to evaluate the expression of E-selectin on human microvascular endothelial cells from the skin (HDMEC) and human umbilical vein endothelial cells (HUVEC) exposed to various concentrations of LPS. In addition, the sensitivity of detection was compared with the most widely used assay for the presence of endotoxin, the Limulus Amebocyte Lysate assay (LAL). The detection of E-selectin on endothelial cells in the presence of LPS for 4 h was found to be at least as sensitive in detecting the same concentration using the LAL assay. A cell adhesion molecule-enzyme immunosorbent assay was also developed and used to quantify LPS using the endothelial cell model. A comparison of LAL and the immunofluorescent staining method was carried out with solutions, nanoparticles, biomaterial extracts and endothelial cells grown directly on biomaterials. Under all conditions, the endothelial/E-selectin model system was positive for the test samples that were positive by LAL. Thus, we propose the use of this highly sensitive, rapid, reproducible assay for the routine testing of endotoxin in all steps in the manufacturing process of materials destined for use in humans. This can give a rapid feedback and localization of bacterial contamination sources with the LAL being reserved for the testing of the final product.     

复方甘草甜素氯化钠注射液的细菌内毒素检查

目的探讨复方甘草甜素氯化钠注射液中细菌内毒素的检查方法。方法选择一定灵敏度的鲎试剂考察复方甘草甜素氯化钠注射液对细菌内毒素检查的干扰作用。结果复方甘草甜素氯化钠注射液对细菌内毒素反应有干扰,将其稀释成1∶8的浓度可消除其干扰作用。结论在1∶8的稀释度下,可用灵敏度为0.25EU.mL-1的鲎试剂进行细菌内毒素检查,从而控制细菌内毒素的限量。     

红花注射液细菌内毒素检查可行性探讨

目的：建立红花注射液静滴用药时细菌内毒素的检查方法、方法：采用2个厂家的鲎试剂对红花注射液进行干扰试验。结果：鲎试剂浓度在0．25EU·mL^-1时，红花注射液经10倍稀释对细菌内毒素测定无干扰。结论：鲎法检测红花注射液静滴用药时的细菌内毒素可行。     

注射用阿奇霉素的细菌内毒素检查法

目的建立注射用阿奇霉素细菌内毒素检查方法。方法按2005年版《中国药典（二部）》中细菌内毒素检查法要求进行试验。结果注射用阿奇霉素（2．0mg／mL）稀释2．8倍时不干扰鲎试剂与细菌内毒素的凝胶反应。结论细菌内毒素检查法适用于检测注射用阿奇霉素中的内毒素。     

鲎试剂的研究及应用进展

鲎试剂已广泛用于细菌内毒素的检验,本文介绍了鲎试剂的生产、分类,用于细菌内毒素检查的反应原理和检测方法、应用领域以及国内外鲎试剂生产和质量的现状和研究进展,并提出了我国鲎试剂应用中急需解决的问题。     

顺铂原料药细菌内毒素检查方法的研究

建立顺铂原料药的细菌内毒素的检查方法.方法参照《中国药典》2005年版二部附录进行.本方法选用灵敏度为0.25EU·mL-1的鲎试剂,供试品浓度在0.25 mg·mL-1 ～1.0 mg·mL-1之间,通过鲎试剂灵敏度复核、预试验、干扰试验和供试品的细菌内毒素检查,结果证明此方法检查顺铂原料药的细菌内毒素可行.     

特异性鲎试剂检测人参多糖注射液中的细菌内毒素

 目的：建立快速的人参多糖注射液细菌内毒素检查法。方法：用特异性鲎试剂对不同批号的人参多糖注射液分别进行干扰试验,考察确立人参多糖注射液内毒素检查法。结果：将人参多糖注射液稀释25倍利用特异性鲎试剂检测可消除干扰作用,结果准确可靠。结论：选用特异性鲎试剂,细菌内毒素检查法代替人参多糖注射液热原检查是可行的。     

注射用头孢哌酮钠他唑巴坦钠中细菌内毒素的检测

目的探讨注射用头孢哌酮钠他唑巴坦钠细菌内毒素的检测方法。方法按照中国药典2000版二部附录细菌内毒素检查法要求，以干扰试验测定。结果本药细菌内毒素限值为0．15EU／ml，在3．333-0．400mg／ml的浓度范围内，不干扰细菌内毒素试验。结论细菌类毒素凝胶法较家兔热原法具有灵敏度高，快速简便易行厦重现性好等优点，本品可用细菌内毒素检查凝胶法代替家兔热原法。     

灯盏细辛注射液中细菌内毒素检测方法的研究

目的对灯盏细辛注射液进行鲎试剂检查法实验,建立灯盏细辛注射液细菌内毒素检查法。方法用不同厂家的鲎试剂对不同批号的灯盏细辛注射液分别进行干扰试验,考察确立灯盏细辛注射液细菌内毒素检查法。结果将灯盏细辛注射液稀释60倍以上可消除干扰作用,检查结果全部为阴性,结果准确可靠。结论灯盏细辛注射液可以用鲎试剂检查法取代家兔热原检查法。