Spectroscopic and computational exploration of hypoxanthine riboside interacting with plasma albumin

Hypoxanthine riboside (HXR) is a nucleoside essential for wobble base pairs to translate the genetic code. In this work, an absorption and luminescence study showed that HXR and human serum albumin (HSA) formed a new complex through hydrogen bonds and van der Waals forces at ground state. Fluorescence probe experiments indicated that HXR entered the first subdomain of domain II in HSA and was fixed by amino acid residues in site I defined by Sudlow, and after competing with a known site marker. The recognition interaction featured negative ΔH^?, ΔS^? and ΔG^? thermodynamic parameters. Fluorescence and circular dichroism spectra described the polarity of residues and α‐helix and β‐strand content changed because of HXR binding. The most rational structure for the HXR–HSA complex was recommended by the molecular docking method, in which the binding location, molecular orientation, adjacent amino acid residues, and hydrogen bonds were included. In addition, the influence of β‐cyclodextrin and some essential metal ions on the balance of the HSA–HXR system interaction was measured. The study gained comprehensive information on the transportation mechanism for HXR in blood, and was of great significance in understanding the theory of HXR biotransformation and in discussing its clinical in vivo half‐life.     

Semiparametric transformation models for interval‐censored data in the presence of a cure fraction

Mixed case interval‐censored data arise when the event of interest is known only to occur within an interval induced by a sequence of random examination times. Such data are commonly encountered in disease research with longitudinal follow‐up. Furthermore, the medical treatment has progressed over the last decade with an increasing proportion of patients being cured for many types of diseases. Thus, interest has grown in cure models for survival data which hypothesize a certain proportion of subjects in the population are not expected to experience the events of interest. In this article, we consider a two‐component mixture cure model for regression analysis of mixed case interval‐censored data. The first component is a logistic regression model that describes the cure rate, and the second component is a semiparametric transformation model that describes the distribution of event time for the uncured subjects. We propose semiparametric maximum likelihood estimation for the considered model. We develop an EM type algorithm for obtaining the semiparametric maximum likelihood estimators (SPMLE) of regression parameters and establish their consistency, efficiency, and asymptotic normality. Extensive simulation studies indicate that the SPMLE performs satisfactorily in a wide variety of settings. The proposed method is illustrated by the analysis of the hypobaric decompression sickness data from National Aeronautics and Space Administration.     

益生菌制剂对轮状病毒性肠炎患儿肠道菌群和免疫功能的影响

目的观察益生菌制剂辅助治疗儿童轮状病毒性肠炎的临床疗效及对患儿肠道菌群和免疫功能的影响。方法以160例轮状病毒性肠炎患儿为研究对象,随机分为对照组(n=80)和研究组(n=80)。对照组患儿给予消旋卡多曲颗粒联合蒙脱石散治疗,研究组患儿在此基础上联合双歧杆菌乳杆菌三联活菌片治疗。观察患儿治疗期间药物不良反应,患儿腹泻停止时间、发热消退时间和呕吐停止时间。分别于治疗前后检测患儿血清免疫球蛋白水平和肠道菌群状况,评价患儿治疗效果。结果研究组患儿腹泻停止时间[(2.41±0.70)d]、发热消退时间[(1.71±0.52)d]和呕吐停止时间[(2.09±0.62)d]均显著短于对照组(均P<0.05)。研究组患儿轮状病毒性肠炎总体治疗有效率显著高于对照组(95.00% vs 83.75%,χ²=5.331,P=0.021)。研究组患儿治疗后血清IgG和IgM水平[(5.83±0.59)g/L和(1.07±0.16)g/L]显著高于对照组(均P<0.05)。研究组患儿治疗后肠道菌群正常者比例显著高于对照组(92.50% vs 76.25%,χ²=8.012,P=0.005)。两组患儿恶心、便秘、皮疹和嗜睡等药物不良反应总体发生率差异无统计学意义(10.00% vs 8.75%,χ²=0.074,P=0.786)。结论益生菌制剂可有效缩短轮状病毒性肠炎患儿临床症状改善周期,提高疗效,改善患儿免疫功能,纠正肠道菌群失调状况,且不增加药物不良反应,值得临床推广使用。     

中国小头蓟马属一新种记述（缨翅目：蓟马科）

记述我国蓟马科小头蓟马属1新种Microcephalothrips yanglingensis,sp.nov，模式标本保存在西北农林科技大学昆虫博物馆。