Biochemical characterization of the recombinant schistosome tegumental protein SmALDH_312 produced in E. coli and baculovirus expression vector system

BackgroundThe heterologous expression of parasitic proteins is challenging because the sequence composition often differs significantly from host preferences. However, the production of such proteins is important because they are potential drug targets and can be screened for interactions with new lead compounds. Here we compared two expression systems for the production of an active recombinant aldehyde dehydrogenase (SmALDH_312) from Schistosoma mansoni, which causes the neglected tropical disease schistosomiasis.ResultsWe produced SmALDH_312 successfully in the bacterium Escherichia coli and in the baculovirus expression vector system (BEVS). Both versions of the recombinant protein were found to be active in vitro, but the BEVS-derived enzyme showed 3.7-fold higher specific activity and was selected for further characterization. We investigated the influence of Mg²⁺, Ca²⁺ and Mn²⁺, and found out that the specific activity of the enzyme increased 1.5-fold in the presence of 0.5 mM Mg²⁺. Finally, we characterized the kinetic properties of the enzyme using a design-of-experiment approach, revealing optimal activity at pH 7.6 and 41°C.ConclusionsAlthough, E. coli has many advantages, such as rapid expression, high yields and low costs, this system was outperformed by BEVS for the production of a schistosome ALDH. BEVS therefore provides an opportunity for the expression and subsequent evaluation of schistosome enzymes as drug targets.How to cite: Harnischfeger J, Beutler M, Salzig D, et al. Biochemical characterization of the recombinant schistosome tegumental protein SmALDH_312 produced in E. coli and baculovirus expression vector system. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.08.002     

Underestimation of Impaired Kidney Function with Serum Creatinine

Serum creatinine (SCr) levels are frequently used as a screening test to assess impaired renal function; however, patients can have significantly decreased glomerular filtration rate (GFR) with normal SCr values and making the recognition of kidney dysfunction more difficult. Hence, this study was designed to determine the extent of misclassification of the patients who have significantly reduced GFR as calculated by reexpressed four variable modification of diet in renal disease (MDRD) equation but, normal range of SCr. The study included 1040 in and out patients referred by physicians for serum creatinine measurement. When an exclusion criterion was applied 928 patients were qualified for the study. SCr was measured in 928 patients by a Roche kinetic compensated Jaffe’s assay. GFR was calculated using reexpressed four variable MDRD study equation. Of the 928 patients 270 (29.1%) had renal dysfunction on the basis of eGFR (<60 ml/min/1.73 m²). However, with SCr only 162 (17.5%) patients had abnormal renal function (>1.5 mg/dl) and SCr values misrepresented (108) 11.6% patients with impaired kidney function. In addition, more females, about 15% were failed to detect by SCr method in contrast to males of 9%. This study documented that, a large proportion of patients with impaired renal function are not diagnosed if clinicians rely solely on normal SCr as evidence of normal renal function. Inclusion of eGFR calculated by re-expressed 4 variable MDRD equation may facilitates the early identification and intervention of patients with renal impairment.     

我国男子铅球优秀运动员背向滑步最后用力时躯干动作的运动学分析

用影像分析等方法对2名男子铅球优秀运动员背向滑步推铅球最后用力过程中躯干转动的动作结构、速度变化等特征进行研究.结果表明,在最后用力阶段,运动员右髋合速度总体趋势上升,达到峰值速度后迅速下降,肩、髋轴的转动幅度在此阶段要远远大于过渡阶段,同时.肩、髋轴的转动速度都迅速增加,肩轴转动速度明显大于髋轴的转动速度,但髋轴先于肩轴达到峰值速度;躯干动作是一种在前振同时进行有序转动的复合运动,右肩的合速度在t1～t2阶段呈下降趋势;人体重心速度的变化在过渡阶段受OY方向的速度影响较大,而受OZ方向的速度影响不大;至最后用力阶段,OY方向身体重心速度迅速下降,OZ方向的身体重心速度急剧上升,而OX方向的人体重心速度对人体重心合速度影响最小.     

荧光法测定脑组织单胺类递质和有关技术问题及其在运动医学中的应用

单胺类递质在大脑许多功能的控制调节中起重要作用,测定不同状态下脑内单胺类递质可了解这类递质在不同状态下脑内的合成、释放和转化,是探索运动性中枢疲劳和有关药物作用机制的重要手段。荧光测定法因其特异性高、操作简单、费用较低等特点,具有广阔的应用前景。但实验中许多值得注意的技术问题和环节影响测定的结果,通过查阅有关文献并结合实验中的影响因素,对其测定的原理、方法和值得注意的有关技术问题及其在医学和生物学中的应用进行梳理和归纳,旨在为应用领域和实验方法学提供理论指导和技术支持。     

体育技术化人文困境的审思

讨论了体育技术化发展使运动损伤加剧的事实,论述了体育技术化对人文关怀忽视的现实;分析了体育技术化人文困境的根源,指出体育发展的功利性,体育对预设的理论规定的僭越以及体育的技术解构与重构而导致的体育伦理价值的颠覆是造成困境的三大主要原因。在此基础上,提出了重塑体育伦理价值理念及实现的行为规范,以及重新确立体育伦理价值评估体系来消解体育技术化人文困境的设想。     

实时BIA技术对蛋白A与免疫球蛋白G相互作用的研究

应用实时BIA技术,探讨了蛋白A与小鼠免疫球蛋白G (MIgG)之间的相互作用,求出相互作用的动力学速率常数ka=5.07×10⁴ (mol/L)^-1s^-1,kd=9.65×10^-5(s^-1),结合常数KA=5.25×10⁸(mol/L)^-1.同时使用蛋白A固定的传感片用于MIgG浓度的检测,在 0.64～ 12mg/L浓度区间内,MIgG的响应值与其浓度有非常好的线性关系.     

实时BIA技术对蛋白A与免疫球蛋白G相互作用的研究

应用实时BIA技术 ,探讨了蛋白A与小鼠免疫球蛋白G (MIgG)之间的相互作用 ,求出相互作用的动力学速率常数ka=5 0 7× 1 0 4 (mol/L) - 1 s- 1 ,kd=9 65× 1 0 - 5(s- 1 ) ,结合常数KA=5 2 5× 1 0 8(mol/L) - 1 .同时使用蛋白A固定的传感片用于MIgG浓度的检测 ,在 0 64～ 1 2mg/L浓度区间内 ,MIgG的响应值与其浓度有非常好的线性关系 .     

三羟甲基乙烷、新戊二醇及其二元体系固—固相变贮热的动力学研究

运用kissinger及Ozawa方法两种热分析动力学模型,利用差示扫描量热法(DSC)测定三羟基乙烷(PG)、新戊二醇(NPG)及其二元体系的低温固一固相变DSC曲线,求算固一固相变的表观活化能和反应级数,探讨表观活化能随组成不同的变化规律。两种方法的处理结果是相一致的。     

水窖底泥中氨氮释放动力学模拟

在不同温度和振荡速度的影响下,水窖底泥中氨氮解吸至上覆水中,会对上覆水造成影响。通过实验分析并探讨了温度和振荡速度对水窖底泥中氨氮释放的影响并进行动力学模拟。实验结果表明：温度和振荡速度增大能够促进水窖底泥中氨氮释放,且氨氮解吸平衡浓度增大;通过准一级动力学方程和准二级动力学方程拟合,两种动力学方程对氨氮释放过程的拟合效果较为接近,且温度影响下两种动力学拟合效果较振荡速度影响好一些（不同温度下其氨氮释放动力学拟合 R2在0．91～0．97,而振荡速度 R20．72～0．94）;因此,窖水的水质可能受到上述因素的影响。实验结果可为窖水水质维护,窖水水质处理等提供理论依据。     

Comparison of two methods of estimation of low density lipoprotein cholesterol, the direct versus friedewald estimation

Current recommendations of the Adult Treatment Panel and Adolescents Treatment Panel of National Cholesterol Education Program make the low-density lipoprotein cholesterol (LDL-C) levels in serum the basis of classification and management of hypercholesterolemia. A number of direct homogenous assays based on surfactant/solubility principles have evolved in the recent past. This has made LDL-C estimation less cumbersome than the earlier used methods. Here we compared one of the direct homogenous assays with the widely used Friedewald’s method of estimation of LDL-C to see the differences and correlation. We used direct homogenous assay kit to estimate serum LDL-C and high-density lipoprotein cholesterol (HDL-C). Serum Triglyceride (TG) and Total Cholesterol (TC) was estimated and using Friedewald’s formula LDL-C was calculated. The LDL-C level obtained by both methods in 893 fasting serum samples were compared. The statistical methods used were paired t-test and Pearson’s correlation. There was significant difference in the mean LDL-C levels obtained by the two methods at the TG levels <200 mg/dl (p<0.02) and TC levels >150 mg% (p<0.001). The correlation coefficient (r) between Friedewald’s and direct assay estimation was 0.88. Friedewald’s method classified 23.5 % of patients as high cardiac risk whereas there were 17.58% by direct assay. Both had good correlation even though the serum triglyceride and total cholesterol levels affect the difference in LDL-C estimated by both methods. Taking into account the cost and performance, Friedewald’s method is as good or even better for classifying and managing patients.