Quantile regression and empirical likelihood for the analysis of longitudinal data with monotone missing responses due to dropout,with applications to quality of life measurements from clinical trials

The analysis of quality of life (QoL) data can be challenging due to the skewness of responses and the presence of missing data. In this paper, we propose a new weighted quantile regression method for estimating the conditional quantiles of QoL data with responses missing at random. The proposed method makes use of the correlation information within the same subject from an auxiliary mean regression model to enhance the estimation efficiency and takes into account of missing data mechanism. The asymptotic properties of the proposed estimator have been studied and simulations are also conducted to evaluate the performance of the proposed estimator. The proposed method has also been applied to the analysis of the QoL data from a clinical trial on early breast cancer, which motivated this study.     

Deferoxamine promotes recovery of traumatic spinal cord injury by inhibiting ferroptosis

Ferroptosis is an iron-dependent novel cell death pathway. Deferoxamine, a ferroptosis inhibitor, has been reported to promote spinal cord injury repair. It has yet to be clarified whether ferroptosis inhibition represents the mechanism of action of Deferoxamine on spinal cord injury recovery. A rat model of Deferoxamine at thoracic 10 segment was established using a modified Allen's method. Ninety 8-week-old female Wistar rats were used. Rats in the Deferoxamine group were intraperitoneally injected with 100 mg/kg Deferoxamine 30 minutes before injury. Simultaneously, the Sham and Deferoxamine groups served as controls. Drug administration was conducted for 7 consecutive days. The results were as follows:(1) Electron microscopy revealed shrunken mitochondria in the spinal cord injury group.(2) The Basso, Beattie and Bresnahan locomotor rating score showed that recovery of the hindlimb was remarkably better in the Deferoxamine group than in the spinal cord injury group.(3) The iron concentration was lower in the Deferoxamine group than in the spinal cord injury group after injury.(4) Western blot assay revealed that, compared with the spinal cord injury group, GPX4, xCT, and glutathione expression was markedly increased in the Deferoxamine group.(5) Real-time polymerase chain reaction revealed that, compared with the Deferoxamine group, mRNA levels of ferroptosis-related genes Acyl-CoA synthetase family member 2(ACSF2) and iron-responsive element-binding protein 2(IREB2) were up-regulated in the Deferoxamine group.(6) Deferoxamine increased survival of neurons and inhibited gliosis. These findings confirm that Deferoxamine can repair spinal cord injury by inhibiting ferroptosis. Targeting ferroptosis is therefore a promising therapeutic approach for spinal cord injury.     

甲状腺乳头状癌伴发桥本甲状腺炎的临床研究

背景与目的：甲状腺乳头状癌（papillary thyroid carcinoma，PTC）和桥本甲状腺炎（Hashimoto’s thyroiditis，HT）的发病率均呈上升趋势，两者之间的关系已成为目前研究的热点。探讨PTC和HT之间的关系。方法：回顾性分析2014—2015年期间在中国科学院大学附属肿瘤医院头颈肿瘤外科行甲状腺癌手术治疗的首诊患者306例，术后病理学检查均明确诊断为PTC，其中术后病理学确诊伴发HT者42例，比较伴发HT与未伴发HT患者的临床病理学特征。结果：PTC患者女性发病年龄高于男性（46.2岁 vs 41.9岁）。相较于与未伴发HT的PTC患者，伴发HT的患者中女性比例更高（93% vs77%），中央区淋巴结数目较多［（5.0±3.4）枚 vs （2.5±2.7）枚］，术前促甲状腺激素（thyroid-stimulating hormone，TSH）水平较高［（3.28±1.91）μU/mL vs （2.12±1.29）μU/mL］，术前抗甲状腺过氧化物酶抗体（thyroid peroxidaseantibody，TPOAb）阳性率较高（55% vs 14%），术前甲状腺球蛋白抗体（thyroglobulin antibodies，TgAb）阳性率较高（69% vs 13%）。发生中央区淋巴结转移的患者中，中央区淋巴结转移数目与中央区淋巴结总数显著相关（Pearson相关系数=0.582）。多因素logistic回归分析发现，男性、低龄、被膜侵犯是PTC患者中央区淋巴结转移的独立危险因素。结论：伴发HT对PTC患者的预后无显著影响。伴发HT的PTC患者TSH水平显著偏高，提示HT可能是PTC发病风险因素之一。中央区淋巴结转移数目与中央区淋巴结总数相关，推测PTC淋巴结转移可能与淋巴结炎症反应相关。