Sensitivity analyses for average treatment effects when outcome is censored by death in instrumental variable models

Two problems that arise in making causal inferences for nonmortality outcomes such as bronchopulmonary dysplasia (BPD) are unmeasured confounding and censoring by death, ie, the outcome is observed only when subjects survive. In randomized experiments with noncompliance and no censoring by death, instrumental variable (IV) methods can be used to control for the unmeasured confounding. But, when there is censoring by death, the average causal treatment effect cannot be identified under usual assumptions but can be studied for a specific subpopulation by using sensitivity analysis with additional assumptions. However, evaluating the local average treatment effect (LATE) in observational studies with censoring by death problems while controlling for unmeasured confounding is not well studied. We develop a novel sensitivity analysis method based on IV models for studying the LATE. Specifically, we present the identification results under an additional assumption and propose a three-step procedure for the LATE estimation. Also, we propose an improved two-step procedure by simultaneously estimating the instrument propensity score (ie, the probability of instrument given covariates) and the parameters induced by the assumption. We show with simulation studies that the two-step procedure can be more robust and efficient than the three-step procedure. Finally, we apply our sensitivity analysis methods to a study on the effect of delivery at high-level neonatal intensive care units on the risk of BPD.     

基于TCMGIS的建泽泻产地适宜性分析

目的 为福建泽泻的科学区划及种植提供产地适宜性分析. 方法选取海拔、土壤、降水量、日照、相对湿度等关键生态因子,应用中药材产地适宜性分析地理信息系统(TCMGIS)进行分析. 结果影响福建泽泻种植的生态因素很多,现产地以建瓯市、建阳市、同安县为主. 结论南平、漳州、三明、龙岩地区适宜大面积推广种植泽泻.     

Fifty Years of Progress in Neonatal and Maternal Transport for Specialty Care

Specialty care for preterm and critically ill infants has evolved over many years. Neonatal intensive care nurseries were developed, and physicians and nurses learned how to provide intensive care for these infants. Neonatal and maternal (in utero) transport to tertiary centers became common in regionalized systems of care to facilitate the specialized care of high-risk neonates when childbirth occurred in settings without specialized personnel or equipment. Annually, nearly 70,000 neonatal transports occur in the United States. Although specialty care helps reduce rates of neonatal mortality, racial disparities and disparities between urban and rural areas exist. The purpose of this article is to review the progress achieved in neonatal and maternal transport over the past 50 years. The knowledge developed can be used to improve the care provided to women, their fetuses, and infants.     

道地产区当归药材品质区域划分

目的:进行当归药材的品质区划研究,指导当归的合理栽培。方法:通过走访和实地调查,从定西市5个县857个样地,采集当归样品857份,使用全球定位系统(GPS)获取采样点信息,超高效液相色谱法(UPLC)测定当归药材8个指标成分含量,结合全国生态因子数据,利用最大熵模型(MaxEnt),SPSS软件,ArcGIS软件进行当归品质适宜性分析。结果:当归的分布适宜区集中在定西市中部及南部,在适宜区范围内阿魏酸、阿魏酸松柏酯、洋川芎内酯H含量由南向北递减;绿原酸含量由北向南递减;洋川芎内酯A,洋川芎内酯I含量由东向西递减;丁烯基苯酞含量规律性不强,含量最高区域在岷县西部、渭源县清源镇、上湾乡、会川镇;藁本内酯在适宜区范围内含量一致性高,含量最高区域在渭源县中部及通渭县北部地区。岷县、漳县、渭源县南部、通渭县北部地区当归药材指标成分含量高,综合品质好。结论:该研究对定西市当归药材品质适宜性进行了等级划分,生成了各指标成分及当归综合品质适宜性区划图,研究结果可为当归药材的综合利用,正确选建优质当归原料基地,科学指导当归药材生产与区域开发提供参考依据。     

基于地形因子的河北省北柴胡生态适宜性区划研究

通过北柴胡中柴胡皂苷类成分含量与地形因子之间的关系,对河北省北柴胡的地形适宜性进行区划研究,为选取种植柴胡的合理区域提供科学的依据。在对河北省43个产地的柴胡实地采样的基础上,应用统计分析方法全面分析了不同地形因子条件下柴胡中柴胡皂苷类成分含量的差异,海拔、坡度、坡向对柴胡皂苷类成分含量的影响,并依据柴胡皂苷类成分与地形因子之间的关系,应用Arc GIS进行了基于地形因子的河北省北柴胡生态适宜性区划。最适宜柴胡皂苷类成分积累的地形因素为海拔(600 m以上)、坡度(4.00~5.50°)、坡向(阳坡),因此,将北柴胡种植在太行山、燕山等地形条件相似的山区地带最为适宜。     

Development of tyrosine hydroxylase-immunoreactive cell populations and fiber pathways in the brain of the dogfish Scyliorhinus canicula: New perspectives on the evolution of the vertebrate catecholaminergic system

Developmental studies of the central catecholaminergic (CA) system are essential for understanding its evolution. To obtain knowledge about the CA system in chondrichthyans, an ancient gnathostome group, we used immunohistochemical techniques for detecting tyrosine hydroxylase (TH), the initial rate‐limiting enzyme of the CA synthesis, to study: 1) the neuromery of developing TH‐immunoreactive (ir) neuronal populations, 2) the development of TH‐ir innervation, and 3) the organization of TH‐ir cells and fibers in the brain of postembryonic stages of the shark Scyliorhinus canicula. The first TH‐ir cells appeared in the hypothalamus and rostral diencephalon (suprachiasmatic, posterior recess and posterior tubercle nuclei at embryonic stage 26, and dorsomedial hypothalamus at stage 28); then in more caudal basal regions of the diencephalon and rostral mesencephalon (substantia nigra/ventral tegmental area); and later on in the anterior (locus coeruleus/nucleus subcoeruleus) and posterior (vagal lobe and reticular formation) rhombencephalon. The appearance of TH‐ir cells in the telencephalon (pallium) was rather late (stage [S]31) with respect to the other TH‐ir prosencephalic populations. The first TH‐ir fibers arose from cells of the posterior tubercle (S30) and formed recognizable ascending (toward dorsal and rostral territories) and descending pathways at S31. When the second half of embryonic development started (S32), TH‐ir fibers innervated most brain areas, and nearly all TH‐ir cell groups of the postembryonic brain were already established. This study provides key information about the evolution of the developmental patterns of central CA systems in fishes and thus may help in understanding how the vertebrate CA systems have evolved. J. Comp. Neurol. 520:3574–3603, 2012. © 2012 Wiley Periodicals, Inc.     

Leapfrog volume thresholds and perioperative complications after radical prostatectomy

BACKGROUND:

The authors explored the effect of Leapfrog volume thresholds (LVTs) on 5 short‐term radical prostatectomy (RP) outcomes.

METHODS:

Within the Health Care Utilization Project Nationwide Inpatient Sample (NIS), the authors focused on RPs performed within the 7 most contemporary years (2001‐2007). They tested rates of in‐hospital mortality, intraoperative complications, postoperative complications, and blood transfusions as well as the mean length of stay (LOS), stratified according to the number of LVTs that were met. Multivariable regression analyses were adjusted further for potential confounders.

RESULTS:

Overall, 36.2%, 17.3%, 14.9%, 15.7%, 12.9%, and 3% of RPs were performed at institutions that reached 0 LVT, 1 LVT, 2 LVTs, 3 LVTs, 4 LVTs, and 5 LVTs, respectively. Relative to patients who underwent RP at institutions that reached 0 LVTs, patients who underwent RP at institutions that reached 5 LVTs had fewer comorbidities, were younger, were more likely to hold private insurance, and were more likely to undergo concomitant pelvic lymphadenectomy (all P < .001). In multivariable analyses adjusted for hospital volume (HV), age, race, year of surgery, Charlson Comorbidity Index, hospital region and location, pelvic lymphadenectomy, and insurance status, LVT status was related inversely to LOS and the likelihood of receiving blood transfusions (both P < .001).

CONCLUSIONS:

The current results indicated that LVTs can provide a highly accurate prediction of the probability of 2 important, detrimental, short‐term outcomes after RP, even after accounting for HV. The benefit at institutions that meet LVTs may exceed that at other institutions when short‐term RP outcomes are considered. This observation should be taken into consideration when treatment decisions are made, especially because most RPs were performed at institutions that did not meet any LVTs. Cancer 2012. © 2012 American Cancer Society.     

基于地形因子的白术生态适宜性区划研究

通过对白术中白术内酯类成分含量与地形因子之间的相关性研究,对白术在全国主产区5省份的地形适宜性进行区划研究,为开展白术种植的合理区域选取提供科学的依据。在对全国5省份40个产地白术实地采样的基础上,应用统计分析方法,全面分析了不同地形因子条件下白术内酯类成分含量的变异,海拔、坡度、坡向对白术内酯类成分含量的影响。并应用空间技术,依据白术内酯类成分与地形因子之间的关系,进行了基于地形因子的白术生态适宜性区划。在我国南方丘陵地区和山区适宜白术生长,白术内酯类成分含量较高,北方平原地区区域内地形条件不适宜白术的生长,但可以将白术种植在区域内地形条件适宜白术的生长的丘陵和山区地带。最适宜白术内酯类成分积累的地形条件为海拔(200 m以上),坡度(3.00~4.99°)。     

基于最大熵模型和地理信息系统的苍术生态适宜性及品质区划

目的：对全国范围内的野生苍术进行生态适宜性和品质区划,为苍术的栽培选址和优质生产提供科学指导。方法：采用文献搜集的方法收集近30年与苍术分布和挥发油含量相关的研究数据,用最大熵模型（MaxEnt）和地理信息系统（GIS）对野生苍术生态适宜性进行区划,并对苍术的适宜种植区和品质形成区进行预测。结果：1）野生苍术最适宜分布区主要集中在燕山山脉、太行山脉、陕北高原南部、秦岭山脉、伏牛山区、大巴山区、桐柏山区、大别山区、茅山周边及黄山周边地区;2）合格野生苍术（苍术素含量>0.30%）最适宜分布区集中在湖北省中部的大洪山、河南省与湖北省交界处的桐柏山和大别山区、安徽省中部的张八岭和江苏省南部的茅山山区至上海的大部分地区,其中大别山区的野生苍术品质差异较大。结论：MaxEnt和GIS对野生苍术生态适宜性分布区预测结果可靠有效。生态环境因子并不是影响苍术品质形成的唯一决定因素,生产合格苍术药材需要有优良的种质资源,以及合适的生态种植环境,如林下、林缘或田间作物套种等。