4D In-Situ Microscopy of Aerosol Filtration in a Wall Flow Filter

The transient nature of the internal pore structure of particulate wall flow filters, caused by the continuous deposition of particulate matter, makes studying their flow and filtration characteristics challenging. In this article we present a new methodology and first experimental demonstration of time resolved in-situ synchrotron micro X-ray computed tomography (micro-CT) to study aerosol filtration. We directly imaged in 4D (3D plus time) pore scale deposits of TiO2 nanoparticles (nominal mean primary diameter of 25 nm) with a pixel resolution of 1.6 μm. We obtained 3D tomograms at a rate of ∼1 per minute. The combined spatial and temporal resolution allows us to observe pore blocking and filling phenomena as they occur in the filter’s pore space. We quantified the reduction in filter porosity over time, from an initial porosity of 0.60 to a final porosity of 0.56 after 20 min. Furthermore, the penetration depth of particulate deposits and filtration rate was quantified. This novel image-based method offers valuable and statistically relevant insights into how the pore structure and function evolves during particulate filtration. Our data set will allow validation of simulations of automotive wall flow filters. Evolutions of this experimental design have potential for the study of a wide range of dry aerosol filters and could be directly applied to catalysed automotive wall flow filters.     

Bone regeneration by means of a three‐dimensional printed scaffold in a rat cranial defect

Recently, computer‐designed three‐dimensional (3D) printing techniques have emerged as an active research area with almost unlimited possibilities. In this study, we used a computer‐designed 3D scaffold to drive new bone formation in a bone defect. Poly‐L‐lactide (PLLA) and bioactive β‐tricalcium phosphate (TCP) were simply mixed to prepare ink. PLLA + TCP showed good printability from the micronozzle and solidification within few seconds, indicating that it was indeed printable ink for layer‐by‐layer printing. In the images, TCP on the surface of (and/or inside) PLLA in the printed PLLA + TCP scaffold looked dispersed. MG‐63 cells (human osteoblastoma) adhered to and proliferated well on the printed PLLA + TCP scaffold. To assess new bone formation in vivo, the printed PLLA + TCP scaffold was implanted into a full‐thickness cranial bone defect in rats. The new bone formation was monitored by microcomputed tomography and histological analysis of the in vivo PLLA + TCP scaffold with or without MG‐63 cells. The bone defect was gradually spontaneously replaced with new bone tissues when we used both bioactive TCP and MG‐63 cells in the PLLA scaffold. Bone formation driven by the PLLA + TCP30 scaffold with MG‐63 cells was significantly greater than that in other experimental groups. Furthermore, the PLLA + TCP scaffold gradually degraded and matched well the extent of the gradual new bone formation on microcomputed tomography. In conclusion, the printed PLLA + TCP scaffold effectively supports new bone formation in a cranial bone defect.     

Estimation of drug receptor occupancy when non-displaceable binding differs between brain regions – extending the simplified reference tissue model

AimThe simplified reference tissue model (SRTM) is used for estimation of receptor occupancy assuming that the non-displaceable binding in the reference region is identical to the brain regions of interest. The aim of this work was to extend the SRTM to also account for inter-regional differences in non-displaceable concentrations, and to investigate if this model allowed estimation of receptor occupancy using white matter as reference. It was also investigated if an apparent higher affinity in caudate compared with other brain regions, could be better explained by a difference in the extent of non-displaceable binding.MethodsThe analysis was based on a PET study in six healthy volunteers using the 5-HT_1B receptor radioligand [¹¹C]-AZ10419369. The radioligand was given intravenously as a tracer dose alone and following different oral doses of the 5-HT_1B receptor antagonist AZD3783. Non-linear mixed effects models were developed where differences between regions in non-specific concentrations were accounted for. The properties of the models were also evaluated by means of simulation studies.ResultsThe estimate (95% CI) of Ki_PL was 10.2 ng ml⁻¹ (5.4, 15) and 10.4 ng ml⁻¹ (8.1, 13.6) based on the extended SRTM with white matter as reference and based on the SRTM using cerebellum as reference, respectively. The estimate (95% CI) of Ki_PL for caudate relative to other brain regions was 55% (48, 62%).ConclusionsThe extended SRTM allows consideration of white matter as reference region when no suitable grey matter region exists. AZD3783 affinity appears to be higher in the caudate compared with other brain regions.     

Toll样受体4及肿瘤坏死因子α在早产儿外周血水平及其与早产儿脑损伤预后的关系

目的观察早产儿出生时外周血Toll样受体4(Toll-like receptor 4,TLR-4)、肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)的水平及校正胎龄6个月龄时智力发育测试(CDCC)结果,探讨其在早产发生机制中的作用及其与早产儿脑损伤预后的关系,为预防早产及对脑损伤早期干预提供依据。方法新生儿120例,分为:足月儿40例、胎膜早破早产儿40例和特发性早产儿40例。采用ELISA检测新生儿外周静脉血中TLR-4、TNF-α的水平,校正胎龄达6个月时做婴幼儿CDCC。结果两组早产儿血清TLR-4、TNF-α水平均高于足月新生儿组,差异有统计学意义(P0.05);两组早产儿血清TLR-4、TNF-α均呈正相关,差异有统计学意义(P0.01)。随访CDCC异常者出生时外周血清中TLR-4、TNF-α水平明显高于正常者水平,二者比较差异有统计学意义(P0.01)。结论早产儿血清TLR-4、TNF-α水平均高于足月新生儿,提示细胞因子TLR-4、TNF-α的激活与胎膜早破早产、特发性早产分娩发动机制密切相关;TLR-4、TNF-α呈正相关性,提示TLR-4可能作为上游因子通过激活细胞因子TNF-α而发挥促进早产分娩的作用。早产儿出生时外周血中TLR-4、TNF-α水平可作为早期判断脑损伤预后的指标。     

空气污染与心率变异性关系的研究进展

心血管疾病是威胁中国居民健康的首要原因,空气污染是影响心血管疾病发生和发展的重要环境危险因素。心率变异性是评价自主神经功能的指标,并且与心血管疾病预后密切相关。研究表明,空气污染可能通过影响心脏自主神经功能而导致心血管疾病的发生,但目前研究结果并不一致。现对国内外空气污染与心率变异性关系的研究现状进行综述。     

2013年北京市某商场空气质量监测与分析

[目的]了解某大型商场的空气质量状况,分析其变化规律及影响因素. [方法]于2013年对北京市某商场空气质量进行监测,监测点为2个商品售卖区和1个餐饮区,监测指标包括温度、湿度、可吸入颗粒物(PM10)、甲醛、一氧化碳(CO)、二氧化碳(CO2),通过远程数据传输技术收集数据并分析. [结果]监测指标中,CO2合格率(100％)最高;其次是温度、PM10、CO和甲醛,合格率分别为98.82％、96.81％、84.73％、69.41％;湿度合格率最低(仅29.36％).商场内不同季节湿度变化明显(P＜0.05); PM10浓度与室外PM10浓度、客流量存在正相关(r=0.681,r=-0.162;P＜0.05);餐饮区CO和CO2浓度高于其他2个监测点,浓度较高的时段与营业高峰时段一致;甲醛浓度波动较大,甲醛最高浓度达0.214 mg/m3,与商场内湿度呈正相关(r=0.740,P＜ 0.05),不同监测点甲醛浓度差异有统计学意义(P＜0.05).[结论] PM10、CO、甲醛是该商场空气质量的主要危害因素.室外PM10浓度和客流量是影响商场内PM10浓度的主要因素;餐饮活动是CO的主要污染来源,客流量增加引起餐饮活动增多间接影响CO浓度;甲醛污染在商场内持续存在,湿度升高加速甲醛释放,局部装修加剧污染程度.商场应采取集中空调分区域运行,及时调整新风量等措施提高空气质量.     

不同粒径大气颗粒物与死亡终点关系的流行病学研究回顾

越来越多的国内外流行病学调查与研究发现,大气颗粒物的暴露与居民不同疾病死亡率的上升存在着显著的相关关系。本文就不同粒径颗粒物与最严重的健康终点——死亡之间关系的流行病学研究,进行较为系统的回顾和评述。指出:大多数研究就可吸入颗粒物(PM10)对死亡终点的影响已进行了较为系统和深入的探讨,目前研究重点向细颗粒物(PM2.5)对健康终点的影响转移。而粗颗粒物(PM10~2.5)以及与PM2.5之间的比较性研究资料还较为有限。超细颗粒物(PM0.1)的暴露及健康影响数据也很有限。但由于其数量浓度的优势,可能会成为未来流行病学研究的重点。     

胶片-报告按需自助打印在放射科的应用

目的：分析胶片-报告按需自助打印技术对放射科取报告过程的流程优化价值。方法：针对放置在放射科入口处的四台自助打印机,观察患者使用及排队情况、胶片匹配识别情况和废弃胶片积压情况,记录机器故障情况。结果：经过一年的使用,每天约有80%患者愿意尝试通过自助打印机取检查结果,其中多数患者使用顺利,并表示愿意下次继续使用。少数情况下,由于患者行动不便、网络故障、耗材不足等因素,造成患者自助取结果失败。结论：胶片-报告自助打印技术在放射科存在许多应用价值,值得推广。同时需重视对设备的定期养护。     

ERK is involved in the differentiation and function of dimethyl sulfoxide-induced HL-60 neutrophil-like cells,which mimic inflammatory neutrophils

Reports show that particulate matter (PM) is related to respiratory and cardiovascular diseases. We previously reported the biological effects of PM in vivo and the endocytosis of PM by primary neutrophils from mice. Cell lines can be used to elucidate the mechanism underlying immune responses in detail; however, information is limited regarding the functions of neutrophils after PM exposure. Here, we investigated the immune response of primary neutrophils and dimethyl sulfoxide (DMSO)- and all-trans retinoic acid (ATRA)-differentiated HL-60 (neutrophil-like) cells to PM. We showed that endocytosis by ATRA-HL cells was enhanced compared to that by DMSO-HL cells and that endocytosis in both cells was inhibited by dynamin inhibitors. A MEK inhibitor, but not p38 or JNK inhibitors, inhibited endocytosis. The MEK inhibitor also inhibited the differentiation of ATRA-HL cells to neutrophils. We identified that endocytosis of PM by neutrophils activated the MAPK ERK and p38 pathways. DMSO-HL and ATRA-HL cells both produced TNF-α and IL-8 after lipopolysaccharide (LPS) or PM treatment, whereas non-differentiated HL-60 cells did not. MCP-1 production was enhanced in DMSO-HL cells after LPS or PM treatment, whereas it was high in ATRA-HL cells. Reactive oxygen species (ROS) production was enhanced after PM treatment to DMSO-HL cells. Further, extracellular extracts promoted endocytosis. The MEK inhibitor also reduced the production of TNF-α, IL-8, and MCP-1. Taken together, ERK activation is key for both differentiation and endocytosis, and DMSO-HL cells at day 6 can serve as a model of inflammatory neutrophils, such as bronchus neutrophils, and a good tool to analyze the molecular events involved in immune responses to PM.