应用吖啶橙- 分光光度法检测重组人白介素- 2制品中SDS含量

目的 用吖啶橙－分光光度法检测重组人白细胞介素－2（rIL－2）制品中Si含量。方法 将被检样品与吖啶橙混合后，加入甲苯进行萃取，然后用紫外分光光度计测　A499吸收峰。结果 在 0-0．o1％SDS浓度范围内，SDS浓度与A400呈线性关系，本法可检测浓度低至 0．001％的 SDS。结论 在一定的 SDS浓度范围内可用吖啶橙-分光光度法检测SDS。     

关于发布《水质氨氦的测定纳氏试剂分光光度法》等三项标准即将实施

《水质氨氮的测定纳氏试剂分光光度法》（HJ535—2009）、《水质氨氮的测定水杨酸分光光度法》（HJ536—2009）、《水质氨氮的测定蒸馏-中和滴定法》（HJ537—2009）三项国家环境保护标准自2010年4月1日起实施。     

紫背天葵中总生物碱含量测定方法的研究

研究了酸性染料直接（有机相）分光光度法、剩余酸性染料（水相）分光光度法,首次提出了剩余酸性染料（水相）-薄层扫描法在紫背天葵中生物碱含量测定中的应用。酸性染料直接（有机相）分光光度法干扰大,测定结果不准确;剩余酸性染料（水相）分光光度法测得紫背天葵干品中总生物碱为0.013%（RSD4.4%,n=3）,平均回收率为97.13%（RSD3.4%,n=3）;剩余酸性染料（水相）-薄层扫描法测得紫背天葵干品中生物碱含量为0.018%（RSD8.5%,n=3）,平均回收率为103.5%（RSD3.0%,n=3）。剩余酸性染料（水相）分光光度法和剩余酸性染料（水相）-薄层扫描法均适合于紫背天葵中总生物碱的测定,操作简便、快速、准确,干扰少,后者还具有需样品量少、有机溶剂用量少的优点。     

FAAS测定氯化铵中的铁和钾

国际氯化铵（GB2946-92）中测定铁的方法较繁琐，采用原子吸收分光光度法（FAAS）可准确地测定氯化铵中的铁和钾，比紫外可见分光光度法和火焰光度法简便快速。     

血红蛋白变性与保护

应用紫外-可见光分光光度法,研究了十二烷基硫酸钠（SDS）导致的牛血红蛋白变性及β-环糊精对血红蛋白与SDS变性过程的影响。研究表明,在蛋白质等电点以下不同pH的PBS缓冲液中,蛋白变性一半所添加的SDS浓度即Cm呈一定的规律性;β-环糊精对蛋白质与SDS相互作用的变性过程有很大的影响,使得牛血红蛋白的Cm值增大,说明β-环糊精对于牛血红蛋白稳定性有一定的保护作用,并且β-环糊精浓度越大,保护作用越强。     

COD测定仪在氯碱废水分析中的应用

用仪器分析（分光光度法）取代容量法测定COD值，用分光光度法测定化学需氧量在技术上是可靠的．大量数据验证了COD测定时用分光光度法与国标容量法的分析结果基本一致，分光光度法可以在氯碱废水分析中应用。     

关于成品硫酸中铁含量测定的思考

工业硫酸的检验采用GB／T534-2002《工业硫酸》（以下简称国标）规定的方法,其中测定铁含量的2种方法分别是邻菲哕啉分光光度法（仲裁法）和原子吸收分光光度法。在成品硫酸的实际检测工作中,我公司质检测中心（以下简称我中心）采用的是邻菲哕啉分光光度法。笔者通过试验和多年的分析经验以及数据积累,     

《水泥原材料中总铬的测定方法》国家标准的制定

《水泥原材料中总铬的测定方法》国家标准的制定,对二苯基碳酰二肼分光光度法、电感耦合等离子体发射光谱法（ICP-OES）和火焰原子吸收分光光度法（AAS）进行了试验研究、试验对比工作,标准中不仅列入了电感耦合等离子体发射光谱法、原子吸收分光光度法,还研究并提出了一种实用性强、准确度高的分光光度法测定水泥原材料中总铬含量的方法,对水泥原材料中总铬的测定具有普适性,测定方法将得到广泛应用。     

饮用水中痕量磷酸盐的固相萃取光度法测定

基于固相萃取分离技术结合分光光度法,建立了一种测定水中痕量磷酸盐的分析方法。磷钼蓝（PMB）与十六烷基三甲基溴化铵（CTMAB）可生成疏水性的PMB—CTMAB离子缔合物,被Sep—PakC18固相萃取小柱富集,用丙酮和硫酸混合液洗脱后分光光度法测定,固相萃取柱不被破坏且可重新处理使用。同时研究了固相萃取条件,讨论了共存离子的干扰及消除。该方法测定饮用水中痕量磷酸盐含量灵敏度高,选择性好,方法的线性范围为0．16～4．00μg／L,检测限为0．052μg／L（n=7）,其相对标准偏差RSD为3．1％～6．2％（n=7）,标准加入回收率为94％～103％,其结果令人满意。     

盐酸多西环素含量测定方法的比较

目的：比较2种测量盐酸多西环素含量方法。方法：紫外分光光度法与高效液相色谱法。结果：紫外分光光度法测盐酸多西环素,在0．002-0．028mg／mL范围内线性关系良好（r=0．9999）,添加回收率为99．12％（n=5,RSD=1．79％）：高效液相色谱法测盐酸多西环素,在0．005-0．180mg／mL范围内线性关系良好（r=0．9999）,添加回收率为99．90％（n=5,RSD=I．76％）。结论：紫外分光光度法操作方便快捷,高效液相色谱法更为可靠。     

共振散射光谱法对视黄醇结合蛋白的测定分析

在pH5.29 Na_2HPO_4-KH_2PO_4缓冲溶液中,羊抗人视黄醇结合蛋白与视黄醇结合蛋白(RBP)发生特异性反应生成免疫复合物微粒,导致体系在340 nm处的共振散射峰显著增强。RBP在0.6~360 ng/m L范围内与ΔI340nm存在良好的线性关系,回归方程为ΔI340nm=1.0063CRBP+9.541,相关系数R为0.996 9,检出限0.1 ng/m L,用于定量分析肾病患者血清中的视黄醇结合蛋白含量,并与免疫透射比浊法比较,结果满意。     

Large Benefit from Simple Things: High-Dose Vitamin A Improves RBP4-Related Retinal Dystrophy

Inherited retinal diseases (IRD) are a group of heterogeneous disorders, most of which lead to blindness with limited therapeutic options. Pathogenic variants in RBP4, coding for a major blood carrier of retinol, retinol-binding protein 4, are responsible for a peculiar form of IRD. The aim of this study was to investigate if retinal function of an RBP4-related IRD patient can be improved by retinol administration. Our patient presented a peculiar white-dot retinopathy, reminiscent of vitamin A deficient retinopathy. Using a customized next generation sequencing (NGS) IRD panel we discovered a novel loss-of-function homozygous pathogenic variant in RBP4: c.255G >A, p.(Trp85*). Western blotting revealed the absence of RBP4 protein in the patient’s serum. Blood retinol levels were undetectable. The patient was put on a high-dose oral retinol regimen (50,000 UI twice a week). Subjective symptoms and retinal function markedly and sustainably improved at 5-months and 1-year follow-up. Here we show that this novel IRD case can be treated by oral retinol administration.     

重组人促红细胞生成素对慢性肾功能衰竭患者营养状态及凝血功能的影响

目的研究重组人促红细胞生成素(r-HuEPO)对慢性肾功能衰竭(CRF)患者营养状态及凝血功能的影响。方法随机抽取CRF患者20名(对照组)及规律使用r-HuEPO CRF患者25名(观察组),测定其血中血红蛋白(Hb)、肌酐(CRE)、视黄醇结合蛋白(RBP)、前白蛋白(PA)、转铁蛋白(TRF)和纤维蛋白原/纤维蛋白降解产物(FDP)浓度,并与对照组比较。结果对照组的Hb、PA、RBP和TRF浓度明显低于观察组,FDP浓度明显高于观察组;两组CRE浓度差异无显著意义;Hb与PA、TRF与RBP浓度呈正相关,与FDP浓度呈负相关;CRE与PA、TRF、RBP和FDP浓度无相关性。结论使用r-HuEPO在纠正CRF患者贫血后,可以改善其营养状态,降低其体内的高凝因素。     

A Genetic Polymorphism in RBP4 Is Associated with Coronary Artery Disease

Insulin resistance and obesity is influenced by the retinol binding protein 4 (RBP4) adipokine. This study aims to determine if genetic polymorphisms in RBP4 are associated with the risk of coronary artery disease (CAD) in Chinese patients. RBP4 polymorphisms were analyzed by high resolution melting (HRM) analysis in a case-control study of 392 unrelated CAD patients and 368 controls from China. The Gensini score was used to determine the severity of CAD. The genotypic and allelic frequencies of RBP4 single-nucleotide polymorphisms were evaluated for associations with CAD and severity of disease. The A allele frequency was significantly higher in CAD case groups compared to control groups (16.7% vs. 8.8%) at the RBP4 rs7094671 locus. Compared to the G allele, this allele was associated with a higher risk of CAD (OR = 2.07 (1.50–2.84)). Polymorphisms at rs7094671 were found to associate with CAD using either a dominant or recessive model (OR, 95% CI: 1.97, 1.38–2.81; 3.81, 1.53–9.51, respectively). Adjusting for sex, history of smoking, serum TC, TG, LDL-c, and HDL-c, the risk of CAD for carriers remained significantly higher in both dominant and recessive models (OR, 95% CI: 1.68, 1.12–2.51; 2.74, 1.00–7.52, respectively). However, this SNP was not significantly associated with severity of CAD using angiographic scores in multivariable linear regression models (p = 0.373). The RBP4 rs7094671 SNP is associated with CAD; however, our results do not indicate that this locus is associated with clinical severity of CAD or the extent of coronary lesions.     

Improved folding of apo-retinol-binding protein in the periplasm of Escherichia coli: positive influences of dsbC coexpression and of an amino acid exchange in the vitamin A binding site

The in vivo folding of the serum retinol-binding protein (RBP), a representative of the lipocalin structural family, is known to be complex. In order to gain insight into the essential steps along its folding pathway the heterologous production of the functional protein in Escherichia coli was investigated. Simultaneous overexpression of the bacterial dsbC gene, which codes for a periplasmic thiol-disulphide oxidoreductase, prevented the formation of soluble RBP variants with non-native disulphide bonds that were otherwise observed. Although the coexpression of dsbC had furthermore a stabilizing effect on the cell viability, the relative yield of the solubly produced RBP was not much better. In an attempt to enhance its folding efficiency, a favourable point mutation in the inner part of the retinol-binding pocket was predicted. Replacement of the polar Gln117 with an lie side chain seemed not only to relieve the unfavourable energetics of the carboxamide group in the environment of predominantly non-polar residues but also to fill an adjacent cavity in the hydrophobic core. Indeed, this single substitution reproducibly resulted in a more than threefold increase in the amount of functional recombinant RBP. Ligand binding experiments showed that the affinity of this mutant for retinol was slightly enhanced. Kinetic measurements revealed that this was due to a higher association rate whereas the dissociation of the complex with retinol was essentially unaffected. Although the question remained why nature did not select this obviously beneficial mutation, our results demonstrate that the folding pathway of a lipocalin can be optimized by protein engineering.      

Exploring Large Domain Motions in Proteins Using Atomistic Molecular Dynamics with Enhanced Conformational Sampling

Conformational transitions in multidomain proteins are essential for biological functions. The Apo conformations are typically open and flexible, while the Holo states form more compact conformations stabilized by protein-ligand interactions. Unfortunately, the atomically detailed mechanisms for such open-closed conformational changes are difficult to be accessed experimentally as well as computationally. To simulate the transitions using atomistic molecular dynamics (MD) simulations, efficient conformational sampling algorithms are required. In this work, we propose a new approach based on generalized replica-exchange with solute tempering (gREST) for exploring the open-closed conformational changes in multidomain proteins. Wherein, selected surface charged residues in a target protein are defined as the solute region in gREST simulation and the solute temperatures are different in replicas and exchanged between them to enhance the domain motions. This approach is called gREST selected surface charged residues (gREST_SSCR) and is applied to the Apo and Holo states of ribose binding protein (RBP) in solution. The conformational spaces sampled with gREST_SSCR are much wider than those with the conventional MD, sampling open-closed conformational changes while maintaining RBP domains’ stability. The free-energy landscapes of RBP in the Apo and Holo states are drawn along with twist and hinge angles of the two moving domains. The inter-domain salt-bridges that are not observed in the experimental structures are also important in the intermediate states during the conformational changes.     

Decrease in serum levels of retinol and its binding protein (RBP) in infection

The main purpose of the present study was to determine the qualitative and quantiative effect of various infectious epsiodes on the blood serum levels of retinol and retinol-binding protein (RBP). Twenty-four children and 30 adult subjects were studied. The infections studied included chickenpox (n = 7); bronchitis (n = 9) upper respiratory infection (n = 30); tonsillitis (n = 2); diarrhea (n = 2) and one case each of: febrile stomatitis, nonspecific gastrointestinal alteration, urinary infection and shigellosis. In addition to retinol and RBP, the study determined changes in serum carotene, proteins, albumin and globulins. The results clearly demonstrate the marked depressing effect of infections on serum retinol, with a magnitude which in many cases reached more than 20 micrograms/dl, and in others more than 30 micrograms/dl. The RBP levels were significantly correlated with retinol, decreasing proportionally with infection. Serum albumin also decreased in most instances; and the globulin levels of the children, but not of the adults, were significantly higher during the infections. Carotene did not show important variations. The effects were more intense when fever accompanied the infectious episodes. These results are considered of great public health significance, in view of the large majorities, mainly children, who ordinarily subsist with very low serum retinol levels in the underdeveloped regions of the world. As infections attack these underpriviledged children, their serum retinol and RBP levels will likely drop a magnitude similar to that observed in the subjects of this study. They may then reach even more critically deficient retinol levels and be in serious danger of developing a severe acute state of clinical vitamin A deficiency.