结肠定位释药双氯芬酸钠包衣片的制备及其体外释放

 目的以3种不同包衣材料制备时间依赖型结肠定位释药包衣片，并考察其体外释放影响因素。方法以双氯芬酸钠为模型药物，分别以乙基纤维素、Surelease和醋酸纤维素为包衣材料制备包衣片，用释放度测定法考察影响药物释放的因素。结果膨胀剂种类、包衣增重和包衣液中致孔剂浓度是影响药物释放的关键因素。3种包衣材料制备的双氯芬酸钠包衣片体外延时时间均可达到5～6 h。结论本实验为时间作为开关的结肠定位释药系统的进一步研究奠定了基础。     

抗菌药的PK/PD理论及其在新抗菌药的药效研究中应用

大约在20年前发现,美国临床和实验室标准化学会发布的关于口服抗菌药的细菌药物敏感性折点,常与临床、微生物学和药代动力学结果不符。因此科学家提出了一个基于药代动力学一药效动力学(PK/PD)模型和临床结果的新方法,并以此推测细菌学转归及细菌学结果与药物敏感性的关系,并将抗菌药分为3种活性类型:①浓度依赖性杀菌和较长的持续效应,其药效依赖于给药量(AUC)或峰浓度与MIC的比值;②时间依赖杀菌却仅有低到中度的持续效应,其疗效更多地依赖于给药次数(血药浓度超过MIC的时间);③时间依赖杀菌而有较长的持续效应,其药效依赖于给药量(AUC)与MIC的比值。对此本文作了介绍。     

Multistate Markov Model for Studying Factors Influencing the Various Progressive Stages of Type 2 Diabetes Mellitus

Objective:To study factors influencing the various pro- gressive stages of type 2 diabetes mellitus in order to pro- vide more concrete scientific bases for the prevention and cure of it. Method:367 subjects with type 2 diabetes mellitus were investigated by retrospective means,and multistate Markov model was used to study factors influencing the transient pace of various progressive stages of type 2 diabetes mellitus. Results:Body mass index,monthly family income, drinking and sweetmeat primarily affected the transition from IGT to DM2.A higher BMI,more monthly family income,more frequent drinking and more intake of sweet- meat were associated with an increasing risk of the transi- tion from IGT to DM2.Monitoring of plasm glucose mostly influenced the transition from DM2 to CDM2.Less frequent monitoring of plasm glucose was associated with an increas- ing risk of the transition from DM2 to CDM2.Staple food, lard,life event,health education and physical-activity level were significantly associated with the transitions both from IGT to DM2 and from DM2 to CDM2.The subjects who took less staple food,more lard,and often experienced irri- table life events were at a higher risk of the two transitions, while those who accepted health education on diabetes mel- litus and had more physical-activity level were at lower risk. Conclusions:For subjects with IGT,controlling weight, rationally allocating family income,abstaining from drinking,and decreasing intake of sweetmeat should be re- garded as primary preventive measures;For ones with DM2,often accepting monitoring of plasm glucose should be considered as leading one.In order to delay the develop- ment and progression of type 2 diabetes mellitus,it is highly necessary to moderately increase intake of cereal or floury food,decrease intake of lard,keep optimistic and unclouded attitude,often listen to lectures on diabetes mellitus,and properly increase physical-activity level.     

白芍总苷长期给药对胶原诱导型关节炎大鼠和正常大鼠肠道菌群影响的纵向研究

目的纵向观察不同剂量白芍总苷(total glucosides of paeony,TGP)给药12周过程中对胶原诱导型关节炎(collagen-induced arthritis,CIA)大鼠以及正常大鼠肠道菌群(简称"菌群")的影响,发现白芍总苷长期给药重点调控的菌群及其代谢功能,以探究其通过影响菌群治疗类风湿关节炎(rheumatoid arthritis,RA)的机制。方法将雄性SD大鼠随机分为正常组、模型组、正常及模型给药白芍总苷(948、474、158 mg·kg^-1)剂量组。于模型复制后给药0周(给药前)以及给药4、8、12周后收集大鼠粪便样本,利用Illumina Miseq平台进行高通量测序,采用相应软件进行操作分类单元(operational taxonomic unit,OTU)、Alpha多样性指数测定,进行Beta多样性分析、基于图形系统发育分析(graphical phylogenetic analysis,GraPhlAn)、偏最小二乘判别分析(partial least squares discriminant analysis, PLS-DA)与线性判别分析(linear discriminant analysis effect size,LEfSe)等的菌群群落结构相似性分析。同时借助数据库进行菌群不同水平分类学组成分析以及PICRUSt(phylogenetic investigation of communities by reconstructing unobserved states)菌群功能的预测。每组先进行不同时间点上述指标的动态变化分析,再进行各组间扣除相同变化后的比较,筛选出白芍总苷对胶原诱导型关节炎和正常大鼠或2个以上剂量调节作用相同的菌群及菌群代谢功能。结果 (1)白芍总苷3个剂量均可影响胶原诱导型关节炎大鼠菌群OTU的经时变化,仅低剂量可影响正常大鼠该指标的经时变化。(2)白芍总苷中、高剂量影响胶原诱导型关节炎大鼠菌群Alpha多样性指数的经时变化,而3个剂量均不影响正常大鼠该指标的经时变化。(3)综合Beta多样性分析以及GraPhlAn、PLS-DA、LEfSe分析,对胶原诱导型关节炎大鼠菌群的影响白芍总苷低、高剂量强于中剂量,对正常大鼠则白芍总苷中、高剂量强于低剂量。Coprococcus属是白芍总苷给药后胶原诱导型关节炎和正常大鼠共同的优势菌属,Akkermansia、Sutterella、Bacteroides、Parabacteroides、SMB53属是不同剂量白芍总苷给药后共同的菌群差异贡献者。(4)不同剂量白芍总苷对胶原诱导型关节炎大鼠各水平分类学组成分析影响呈剂量依赖性,对正常大鼠则作用相近;白芍总苷低、中剂量对胶原诱导型关节炎和正常大鼠菌群影响均不同,而高剂量对两者的Peptococcaceae科、Coprococcus属影响明显。(5)胶原诱导型关节炎大鼠升高的Biosynthesis of Other Secondary Metabolites菌群代谢功能(以下简称"功能"),可被中剂量白芍总苷降低;3个剂量白芍总苷均明显升高胶原诱导型关节炎大鼠Endocrine System功能,中、高剂量均明显升高Immune System功能,低、高剂量均明显降低Cardiovascular Diseases、Cellular Processes and Signaling功能。高剂量白芍总苷降低正常和胶原诱导型关节炎大鼠中Immune System Diseases功能。结论白芍总苷对胶原诱导型关节炎大鼠的菌群调节作用强于正常大鼠。上述白芍总苷长期给药稳定和重点调节的菌群和菌群代谢功能解释了其对类风湿关节炎的疗效,不同剂量白芍总苷明显影响的菌群和菌群代谢功能不同。     

The population-attributable fraction for time-dependent exposures and competing risks—A discussion on estimands

The population-attributable fraction (PAF) quantifies the public health impact of a harmful exposure. Despite being a measure of significant importance, an estimand accommodating complicated time-to-event data is not clearly defined. We discuss current estimands of the PAF used to quantify the public health impact of an internal time-dependent exposure for data subject to competing outcomes. To overcome some limitations, we proposed a novel estimand that is based on dynamic prediction by landmarking. In a profound simulation study, we discuss interpretation and performance of the various estimands and their estimators. The methods are applied to a large French database to estimate the health impact of ventilator-associated pneumonia for patients in intensive care.     

Nosocomial infections in a Dutch neonatal intensive care unit: surveillance study with definitions for infection specifically adapted for neonates

The incidence of nosocomial infection in neonatal intensive care units (NICUs) is high compared with other wards. However, no definitions for hospital-acquired infection are available for NICUs. The aim of this study was to measure the incidence of such infections and to identify risk factors in the NICU of the VU University Medical Center, which serves as a level III regional NICU. For this purpose, a prospective surveillance was performed in 1998-2000. We designed definitions by adjusting the current definitions of the Centers for Disease Control and Prevention (CDC) for children <1 year of age. Birth weight was stratified into four categories and other baseline risk factors were dichotomized. Analysis of risk factors was performed by Cox regression with time-dependent variables. The relationship between the Clinical Risk Index for Babies (CRIB) and nosocomial infection was investigated. Furthermore, for a random sample of cases, we determined whether bloodstream infection and pneumonia would also have been identified with the CDC definitions. Seven hundred and forty-two neonates were included in the study. One hundred and ninety-one neonates developed 264 infections. Bloodstream infection (N=138, 14.9/1000 patient-days) and pneumonia (N=69, 7.5/1000 patient-days) were the most common infections. Of bloodstream infections, 59% were caused by coagulase-negative staphylococci; in 21% of neonates, blood cultures remained negative. In 25% of pneumonias, Enterobacteriaceae were the causative micro-organisms; 26% of cultures remained negative. Compared with the Nosocomial Infections Surveillance System (NNIS) of the CDC, our device utilization ratios and device-associated nosocomial infection rates were high. The main risk factors for bloodstream infection were birth weight [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.45-2.17] and parenteral feeding with hospital-pharmacy-produced, all-in-one mixture 'Minimix' (HR 3.69, 95%CI 2.03-6.69); administration of intravenous antibiotics (HR 0.39, 95%CI 0.26-0.56) was a protective risk factor. The main risk factors for pneumonia were low birth weight (HR 1.37, 95%CI 1.01-1.85) and mechanical ventilation (HR 9.69, 95%CI 4.60-20.4); intravenous antibiotics were protective (HR 0.37, 95%CI 0.21-0.64). In a subcohort of 232 very-low-birthweight neonates, the CRIB was not predictive for infection. With the CDC criteria, only 75% (21/28) of bloodstream infections and 87.5% of pneumonias (21/24) would have been identified. In conclusion, our local nosocomial infection rates are high compared with those of NICUs participating in the NNIS. This can be partially explained by: (1) the use of our definitions for nosocomial infection, which are more suitable for this patient category; and (2) the high device utilization ratios.     

Partitioned GMM logistic regression models for longitudinal data

Correlation is inherent in longitudinal studies due to the repeated measurements on subjects, as well as due to time-dependent covariates in the study. In the National Longitudinal Study of Adolescent to Adult Health (Add Health), data were repeatedly collected on children in grades 7-12 across four waves. Thus, observations obtained on the same adolescent were correlated, while predictors were correlated with current and future outcomes such as obesity status, among other health issues. Previous methods, such as the generalized method of moments (GMM) approach have been proposed to estimate regression coefficients for time-dependent covariates. However, these approaches combined all valid moment conditions to produce an averaged parameter estimate for each covariate and thus assumed that the effect of each covariate on the response was constant across time. This assumption is not necessarily optimal in applications such as Add Health or health-related data. Thus, we depart from this assumption and instead use the Partitioned GMM approach to estimate multiple coefficients for the data based on different time periods. These extra regression coefficients are obtained using a partitioning of the moment conditions pertaining to each respective relationship. This approach offers a deeper understanding and appreciation into the effect of each covariate on the response. We conduct simulation studies, as well as analyses of obesity in Add Health, rehospitalization in Medicare data, and depression scores in a clinical study. The Partitioned GMM methods exhibit benefits over previously proposed models with improved insight into the nonconstant relationships realized when analyzing longitudinal data.     

Effect of Angiotensin II Inhibitors on Gastrointestinal Bleeding in Patients With Left Ventricular Assist Devices

Background

Angiotensin II receptor activation may result in angiogenesis, and ultimately arteriovenous malformations (AVM), through transforming growth factor (TGF)-β and angiopoietin-2 pathway activation.